Problem merging two different Seurat objects and creating a CellChat object. Result obtained: 0 signaling genes.

[Humph18]

I'm trying to create a cellchat with two different Seurat objects (combined_healthy and merged_seurat). First, I checked that each cell chat separately has genes once I made the Cellchat object. Then, I have been following the tutorial "Comparison analysis of multiple datasets with different cell type compositions" and based on the script I lift up the combined_healthy (with 8 idents) with the levels from merged_seurat (11 idents). However, once I merge and create the cellchat object the result is 0 signalling genes. Does anyone know how to fix it? Thanks in advance for your help!
Here I copy my script.

#Load LM seurat object
#Load Healthy seurat object

#CellChat script
rm(list=ls()[! ls() %in% c("combined_healthy","merged_seurat")])
combined_healthy <- RenameIdents(combined_healthy,
list( "0"= "Immune",
"1"="Immune",
"2"="LSECs",
"3"="HSCs",
"4"= "LSECs",
"5"="LSECs",
"6"="Immune",
"7"="Prolif",
"8"="LSECs"))

merged_seurat <- RenameIdents(merged_seurat,
list( "0"= "Kupffer",
"1"="Mix",
"2"="Immune",
"3"="Mix",
"4"= "Mix",
"5"="HSCs",
"6"="Prolif-Immune",
"7"="Immune-LSECs",
"8"="Prolif-Immune",
"9"="Endothelial",
"10"="Endothelial",
"11"="LSECs",
"12"="Immune-LSECs",
"13"="Immune"))

cellchat_healthy <- createCellChat(object = combined_healthy, group.by = "ident", assay = "RNA")
cellchat_LM <- createCellChat(object = merged_seurat, group.by = "ident", assay = "RNA")

Define the cell labels to lift up by combining both cell labels from the conditions. Due to I have different levels I used the function union

group.new = union(levels(cellchat_LM@idents), levels(cellchat_healthy@idents))
cellchat_healthy <- liftCellChat(cellchat_healthy, group.new)

object.list <- list(NL = cellchat_healthy, LS = cellchat_LM)
cellchat <- mergeCellChat(object.list, add.names = names(object.list))
cellchat