Input just randomly doesn't work

I have a standard Xinput controller. Under Device Index I have Xinput Controller (User 1) #1, so it sees the device, but it just doesn’t work. It worked the other day. Today it doesn’t. Sometimes I play on Steam Link, so the controller changes, but this has worked in the past.

Basically, what I’m asking - pleading for - is can someone explain the PHD-level confusion-fest that is the input situation in RetroArch?

I’ve never had any dropouts with xinput pads. Can you get a log that shows when it works vs not?

I’ve managed to get it working by using Steam to apply a standard 360 mapping to the controller (which by the way is a MadCatz Fightpad). I think this way works best because I can also play through Steam Link with a PS4 controller (also with a standard 360 mapping applied to it by Steam).

If I just run RetroArch without going through Steam, the controller just doesn’t work.