diff --git a/include/flamegpu/simulation/AgentVector_Agent.h b/include/flamegpu/simulation/AgentVector_Agent.h
index d8e7aee2d..317c92224 100644
--- a/include/flamegpu/simulation/AgentVector_Agent.h
+++ b/include/flamegpu/simulation/AgentVector_Agent.h
@@ -249,6 +249,8 @@ void AgentVector_Agent::setVariable(const std::string &variable_name, const unsi
     }
     _parent->_require(variable_name);
     static_cast<T*>(v_buff->getDataPtr())[(index * (v_buff->getElements() / detail::type_decode<T>::len_t)) + array_index] = value;
+    // Notify (_data was locked above)
+    _parent->_changed(variable_name, index);
 }
 #ifdef SWIG
 template <typename T>
diff --git a/src/flamegpu/io/Telemetry.cpp b/src/flamegpu/io/Telemetry.cpp
index cc2b292ee..eb37f5709 100644
--- a/src/flamegpu/io/Telemetry.cpp
+++ b/src/flamegpu/io/Telemetry.cpp
@@ -372,8 +372,7 @@ std::string Telemetry::getUserId() {
                     return cached_id;
                 else
                     return userId;
-            }
-            else {
+            } else {
                 throw std::runtime_error("Unable to open user ID file for reading");
             }
         }
@@ -382,8 +381,7 @@ std::string Telemetry::getUserId() {
         if (file.is_open()) {
             file << userId;
             file.close();
-        }
-        else {
+        } else {
             throw std::runtime_error("Unable to create user ID file");
         }
     } catch (const std::exception&) {
diff --git a/tests/test_cases/runtime/agent/test_device_agent_vector.cu b/tests/test_cases/runtime/agent/test_device_agent_vector.cu
index 0181384c1..0c05c9ccd 100644
--- a/tests/test_cases/runtime/agent/test_device_agent_vector.cu
+++ b/tests/test_cases/runtime/agent/test_device_agent_vector.cu
@@ -22,6 +22,24 @@ FLAMEGPU_STEP_FUNCTION(SetGet) {
         ai.setVariable<int>("int", ai.getVariable<int>("int") + 12);
     }
 }
+FLAMEGPU_STEP_FUNCTION(SetGetArray) {
+    // Accessing DeviceAgentVector like this would previously lead to an access violation (Issue #522, PR #751)
+    DeviceAgentVector av = FLAMEGPU->agent(AGENT_NAME).getPopulationData();
+    for (AgentVector::Agent ai : av) {
+        auto t = ai.getVariable<int, 3>("int");
+        t[0] += 11;
+        t[1] += 12;
+        t[2] += 13;
+        ai.setVariable<int, 3>("int", t);
+    }
+}
+FLAMEGPU_STEP_FUNCTION(SetGetArrayElement) {
+    // Accessing DeviceAgentVector like this would previously lead to an access violation (Issue #522, PR #751)
+    DeviceAgentVector av = FLAMEGPU->agent(AGENT_NAME).getPopulationData();
+    for (AgentVector::Agent ai : av) {
+        ai.setVariable<int, 3>("int", 1, ai.getVariable<int, 3>("int", 1) + 12);
+    }
+}
 FLAMEGPU_STEP_FUNCTION(SetGetHalf) {
     HostAgentAPI agent = FLAMEGPU->agent(AGENT_NAME);
     DeviceAgentVector av = agent.getPopulationData();
@@ -77,6 +95,85 @@ TEST(DeviceAgentVectorTest, SetGet) {
         ASSERT_EQ(av[i].getVariable<int>("int"), static_cast<int>(i) + 24);
     }
 }
+TEST(DeviceAgentVectorTest, SetGetArray) {
+    // Initialise an agent population with values in a variable [0,1,2..N]
+    // Inside a step function, retrieve the agent population as a DeviceAgentVector
+    // Update all agents by adding 12 to their value
+    // After model completion, retrieve the agent population and check their values are [12,13,14..N+12]
+    ModelDescription model(MODEL_NAME);
+    AgentDescription agent = model.newAgent(AGENT_NAME);
+    agent.newVariable<int, 3>("int", { 0, 0, 0 });
+    model.addStepFunction(SetGetArray);
+
+    // Init agent pop
+    AgentVector av(agent, AGENT_COUNT);
+    for (unsigned int i = 0; i < AGENT_COUNT; ++i)
+        av[i].setVariable<int, 3>("int", { 0, static_cast<int>(i), 0 });
+
+    // Create and step simulation
+    CUDASimulation sim(model);
+    sim.setPopulationData(av);
+    sim.step();
+
+    // Retrieve and validate agents match
+    sim.getPopulationData(av);
+    for (unsigned int i = 0; i < AGENT_COUNT; ++i) {
+        const std::array<int, 3> t1 = {11, static_cast<int>(i) + 12, 13 };
+        const std::array<int, 3> t2 = av[i].getVariable<int, 3>("int");
+        ASSERT_EQ(t1, t2);
+    }
+
+    // Step again
+    sim.step();
+
+    // Retrieve and validate agents match
+    sim.getPopulationData(av);
+    for (unsigned int i = 0; i < AGENT_COUNT; ++i) {
+        const std::array<int, 3> t1 = { 22, static_cast<int>(i) + 24, 26 };
+        const std::array<int, 3> t2 = av[i].getVariable<int, 3>("int");
+        ASSERT_EQ(t1, t2);
+    }
+}
+TEST(DeviceAgentVectorTest, SetGetArrayElement) {
+    // Covers former bug, where updating an array element would not trigger sync
+    // Initialise an agent population with values in a variable [0,1,2..N]
+    // Inside a step function, retrieve the agent population as a DeviceAgentVector
+    // Update all agents by adding 12 to their value
+    // After model completion, retrieve the agent population and check their values are [12,13,14..N+12]
+    ModelDescription model(MODEL_NAME);
+    AgentDescription agent = model.newAgent(AGENT_NAME);
+    agent.newVariable<int, 3>("int", {0, 0, 0});
+    model.addStepFunction(SetGetArrayElement);
+
+    // Init agent pop
+    AgentVector av(agent, AGENT_COUNT);
+    for (unsigned int i = 0; i < AGENT_COUNT; ++i)
+        av[i].setVariable<int, 3>("int", { 0, static_cast<int>(i), 0 });
+
+    // Create and step simulation
+    CUDASimulation sim(model);
+    sim.setPopulationData(av);
+    sim.step();
+
+    // Retrieve and validate agents match
+    sim.getPopulationData(av);
+    for (unsigned int i = 0; i < AGENT_COUNT; ++i) {
+        const std::array<int, 3> t1 = { 0, static_cast<int>(i) + 12, 0 };
+        const std::array<int, 3> t2 = av[i].getVariable<int, 3>("int");
+        ASSERT_EQ(t1, t2);
+    }
+
+    // Step again
+    sim.step();
+
+    // Retrieve and validate agents match
+    sim.getPopulationData(av);
+    for (unsigned int i = 0; i < AGENT_COUNT; ++i) {
+        const std::array<int, 3> t1 = { 0, static_cast<int>(i) + 24, 0 };
+        const std::array<int, 3> t2 = av[i].getVariable<int, 3>("int");
+        ASSERT_EQ(t1, t2);
+    }
+}
 TEST(DeviceAgentVectorTest, SetGetHalf) {
     // Initialise an agent population with values in a variable [0,1,2..N]
     // Inside a step function, retrieve the agent population as a DeviceAgentVector