Roon 1.8 (756) works on Macos 11.2.1 but not at all on iPadOS 14.4

Roon 1.8 (latest build) after two days now works perfect on my iMac and Macbook. However, as soon as I start Roon on iPad, the control buttons at the bottom disappear on all devices (including the Macs) as well as the progress barr freezes. This happens only when playing music from my own library, not when playing from Tidal or Qobuz.