this sounds a lot like the problems i am having. i have not moved to UAE yet.
seeing that they said Amiberry was the easiest one to setup.

Problems with it after getting it all worked out and setup then getting the Amiberry installed with the installer "Manage optional Packages" so now have Amiga folder showing up to put the games .LHA E:\retropie\roms\amiga with a jump drive
and putting the kickstart files in the jump drive E:\retropie\BIOS
so all seems good i looked at the files on the Pi and they seem to have copied over good and in the place it said they should be is there another place to put them???

but when i try and run a game.

it goes to a black screen and then winks back to the pick a game screen.
if i keep clicking on the A key it loads up a screen "System: Amiga" asking to select "default emulator" ES, ER,
VE, FE, FR, X, Q.
so when looking "ER" at Bios the names to not match the ones i uploaded. thinking it would be named the same as the ones uploaded.
not sure if this is the problem. do i need to do something other than just putting them in that folder???
(( Please help)) i seen something that the updater is not using the newest one will start looking at that.

my system is a Raspberry Pi3 B+ in the USA.
Hisense 4 K HDMI tv
XBox corded controller. Keyboard and mouse.
have been doing like the video said using the USB jump drive to move files over. "Raspberry Pi 4 Retropie - Amiberry Setup MikeyGRetro"
and use many other videos to help with setting up Retropie on the Raspberry Pi 3b+ "RetroPie 4.8 Setup and Install Guide for the Raspberry Pi" Wagner's TechTalk.

i have had UAE for Droid on my phone for 10 years i think. with the Amiga forever Kickstarts. but made a cool 3D printed Amiga case for my Pi 3b+ and wanted something i could use on the TV and the kids could play.
i do have Amibian working on another flash card on the Pi 3+ but just not as easy to use as the videos said RetroPie is. and this would be good. have seen some info on the site saying need to use the numerical updater seeing the auto one is not working right??

UAE + Amiga in a box.