MIDI clock desync

Hello,

I have an older iPad Air, model A1474, running the most recent Cubasis 2. Everything seems to work well except the MIDI clock sync with external hardware. The sync signal transmission seems to be significantly slower than the playback within Cubasis, and will drift completely out of sync within a few bars. The external hardware syncs with other apps, such as AUM, over MIDI so I don’t believe the problem is related to the hardware (either the iPad or the MIDI gear). I tried fiddling with the sync latency setting, but that doesn’t help.

Any help would be much appreciated, thanks.