Okay. The button is not missing, LED on the Vu+ Box is indicating that it gets a signal, but no reaction. So I recorded the Cursor Up button, but it is different every time I hit the button? No idea how this works, but I assume this is correct...
I can confirm that this is the right button for Uno 4K (not SE) and Solo SE (V1)... so maybe you could copy a working profile and just change the cursor up?
(But I think this would be right for all working profiles)
Working profiles for Uno 4K (not SE) and Soloe SE (V1): Most Models, Solo 4K, Solo SE V2, Ultimo 4K, Ultimo/Duo2/Solo2, Uno 4K SE, Zero 4 K
Not working at all: Duo+, Uno and Duo
my_flirc_log__VUplus_Uno4K_CursorUp.txt