Audioinjector no input sound

I’m using an audioinjector soundcard and output works fine, but I couldn’t get the input to work. Neither over MOD-UI nor over the “record audio” tool in the menu.

I’m using a raspi 4 and here are my zynthian versions:

SOFTWARE

zyncoder: [master (f01eb07)](https://github.com/zynthian/zyncoder/commit/f01eb074d851c33cf2674be8555e76e025ede1df)
zynthian-ui: [master (d82d176)](https://github.com/zynthian/zynthian-ui/commit/d82d17670abc21aaf6f892893a7c9ccf3a280968)
zynthian-sys: [master (011666c)](https://github.com/zynthian/zynthian-sys/commit/011666ce8f942022688fdd25cccbd31b28a6b8ac)
zynthian-data: [master (c8d15e7)](https://github.com/zynthian/zynthian-data/commit/c8d15e7813b9810939667f0396b375640c9587d3)
zynthian-webconf: [master (21a234a)](https://github.com/zynthian/zynthian-webconf/commit/21a234a2d27479d46000267cfca669a40abefcb3)

Already checked the alsamixer, but it looks fine (compared it to here)

Any hints on where to start fixing that? I already installed the drivers from the github page and changed to RCA with their script.