Intermittent fullscreen exit issue in JsPsych Experiment

[LuoweiY]

Hello!

I am hosting an online experiment written in JsPsych on JATOS. The experiment begins in FullScreen mode and exits FullScreen only after all demographics screens have been completed. However, some participants reported that FullScreen mode unexpectedly exited after finishing the first screen of the demographics section ("survey-text"), even though it should continue to the next screens ("survey-multi-choice" and "survey-text"). Interestingly, the majority of participants were able to complete the experiment without issues. Please see attached my component code.

I have not been able to figure out why this occurs. Would you have any idea what might be causing this intermittent issue, and how I could resolve it? Thanks!

		/* fullscreen */
		var inner_pos, outer_pos, scr_width, scr_height, img_width, img_height;
		timeline.push({
			type: "fullscreen",
			fullscreen_mode: true,
			message: 
				"<p>If you unintentionally exit fullscreen or due to glitches during the experiment,</p>" + 
				"<p>please contact the experimenter directly and <b>DO NOT</b> restart the experiment.</p><br>"+
				"<p>The experiment will switch to full screen mode when you press the button below. </p>" +
				"<p><b>Please do not exit out of fullscreen mode, or the experiment will be terminated immediately.</b></p>" +
				"<p>We will put it back to its regular size at the end of the experiment.</p><br><br>",
			data: {screen: "fullscreen_on"}
		});

		/* demographics */
		var demo_p1 = {
			type: "survey-text",
			data: { screen: "demo_p1" },
			questions: [
				{prompt: "How old are you?", name: "Age", required: true, 
				rows: 1, columns: 5}]
		};
		timeline.push(demo_p1);

		var demo_p2 = {
			type: "survey-multi-choice",
			data: { screen: "demo_p2" },
			questions: [
				{prompt: "What gender do you identify with? ", name: "Gender", 
				options: ["Man","Woman","Other"],required: true},
				{prompt: "<br/>What is your ethnicity origin? ", name: "Ethnicity", 
				options: ["White","Asian","Black","Mixed","Other"],required: true},
				{prompt: "<br/>Handedness ", name: "Handedness", 
				options: ["Right","Left","Ambidextrous"],required: true}]
		};
		timeline.push(demo_p2);

		var demo_p3 = {
			type: "survey-text",
			data: { screen: "demo_p3" },
			questions: [
				{prompt: "Did you notice anything interesting during the experiment you wanted to share?", 
				name: "comment", required: false, rows: 7, columns: 80},
				{prompt: "Did you experience any technical issues or interruptions during this experiment (e.g., images not showing up at the same time)?", 
				name: "issues", required: false, rows: 7, columns: 80}]
		};
		timeline.push(demo_p3);

		/* close fullscreen */
		var ok = 0
		timeline.push({
			type: "fullscreen",
			on_start: function(){
				ok = 1
			},
			fullscreen_mode: false,
			data: {screen: "fullscreen_off"}
		});

		/* Start the Experiment */
		jsPsych.init({				
			timeline: timeline,
			preload_images: all_imgs_list,
			on_trial_finish: function(data){
				if ((jsPsych.data.getInteractionData().json()).includes("fullscreenexit") & ok == 0){
					var resultDataStr = jsPsych.data.get().csv();
					jatos.submitResultData(resultDataStr).done(function() {
						jatos.endStudy(false, "Your experiment is terminated because you exited fullscreen mode.")
					});
				}
			},
			on_finish: function() {
				// Submit the result data as CSV first, end the study and redirect
				var resultDataStr = jsPsych.data.get().csv();
				jatos.submitResultData(resultDataStr).done(function() {
					var end_red;
					if (platform == "sona") {
						if (typeof sub_id === 'undefined') {
							end_red = "URL link";
						} else {
							end_red = "URL link" + sub_id;
						}
					} else if (platform == "prolific") {
						end_red = "URL link";
					}
					// jatos.endStudyAndRedirect(end_red);
				
					window.open(end_red, '_blank');
					jatos.endStudy();
				});
			}
		});