Hey @Damijan,
Thanks for the update! I’m glad to hear you’re able to sync with Arc generally.
ARC can typically handle large libraries, but there are some practical limitations once you get into the hundreds of thousands of tracks that we’re still facing, and actively working on improving. The main challenge isn’t ARC itself; it’s the way mobile platforms (Apple and Google) manage background data and sync for apps. They impose quotas and throttling that can interrupt the process when libraries are extremely large.
In real-world terms, libraries over about 250k tracks may experience issues with ongoing syncs, especially after the initial setup. The most reliable way to work around this is to maintain a full offline mirror of your library, but even then, large updates will still depend on those background transfer limits.
We’re actively looking for ways to improve this, but if you’re working with around 500k tracks, we can’t guarantee proper, reliable syncing at this time.
I realize this is less than ideal, you do have my apologies here!