Thanks for taking the time to write in and share your report!
As @Suedkiez has mentioned - the current version of Arc on your device is quite out of date! As an immediate next step, can you please try performing a system reset on the DAP and see if it updates properly for you?
@benjamin My ARC is 1.0.59, this is from October 2024 - I wouldn’t call that “quite out of date”.
I have resolved the problem in a different way: I disconnected from the current server, and reconnected again. That fixed the problem, and after a few hours of initial sync, roon arc is now working.
I do think that this was a different problem than the one of an old ARC.
Anyway, I will update to the latest 1.0.61, but you could provide the .apk file for download somewhere more easily than the need to go through apkpure or other third party stores, a link from the website would be great.
Maybe “ancient” was the wrong word, but all Roon apps (server and control apps including ARC) in principle need to come from the same Roon release. An older one may sometimes work, but even a 3 month old one may not work if Roon makes incompatible changes in a more recent server update.