How to add option for selecting from different blueprint class

I tried using a combobox and set the value in a actor variable , image 1
I just made visible by adding in startMenu blueprint by adding a branch , image 2
I tried getting the modelAR variable from BP_selectModel blueprint where I created the combobox and put the value in spawn actor in BP_ARPawn, the app is running but nothing shows up after model placement, or by selecting different options in the combobox, I am editing on the demo handheld AR project which shows up on game when you start unreal.

I am absolutely new to this, I haven’t done anything other that directly following the tutorials.