I have been using steamlink on a raspi 3 with retropie installed for a while. It was working great and recognized all connected controllers.

Since one or two months (version 1.1.96 I think), steam does not recognize a 3rd party snes controller anymore. Version 1.2.0.241 did not solve the problem.

For me it seems like steam link is even breaking something in Linux. The controller refuses to work in emulationstation once steam link is closed (even when steam link never connected to any pc). Only thing which helped was a reboot of the raspi.

Any advice what to do or how to further debug the issue?

Cross post in raspi forum:
https://steamcommunity.com/app/353380/discussions/6/3716063