Hello, I DID found the solution in the end. Following similar topics on the forum (this one in particular: https://discuss.getsol.us/d/10154-support-printer-epson-stylus-photo-rx520/49), I discovered the package SANE-Backends was... preventing Solus to see my printer? I removed the package, rebooted, and now it works! Problem is apparently, if I want to scan anything I'll need to reinstall the package. But since I don't need to scan anything, it's okay for me. It's a bug that I hope will be addressed in the near future, because I guess loads of people will want to scan and print documents at the same time ^^ Still, for me, it's all good now! Thanks @Axios for finding the solution.
