4 xbox 360 controllers - works on N64 but not PCSX

I have four Xbox 360 controllers connected wirelessly to the adapter shown below (generic, Chinese adapter). I am using an old laptop running Lakka from LiveUSB. After trying a bunch of other controller options (XB1 BT was flakey, as were the USB-PCX wired controllers), I am so close to getting this working!

I can play four player N64 games without problem. However, I can’t get the third and fourth controllers to work on PCSX games (Crash Bash, CTR). I have Multitap turned on on the game options and the controllers are configured identically. The game detects that I have a third and fourth controller connected (I can select 4 players for example) but when I try to select a character, the pointer does not move.

I don’t think it’s the adapter given that I can get N64 games to work without issue.

Can anyone help point me in the right direction?

BTW huge thanks to everyone who worked on any and all the pieces of this amazing project, my wife was super impressed that we could get these old games working!

Next stop: RPi3B+