Actual BPM faster than reported tempo

I’ve noticed something unusual with the BPM in Cubasis. It’s running slightly faster than the reported tempo.

I first noticed when trying to manually sync Cusasis and Ableton Live. With both programs running and the metronome enabled on each, the Ableton metronome would drift out of time and end up running slower than the Cusasis metronome. I’m not trying any kind of MIDI clock sync here, btw. Just running each independently at the same BPM and manually beatmatching the metronome ticks using the ‘nugde’ in Ableton.

At this point, I wasn’t sure if it was a problem with Ableton Live or Cubasis so I set the tempo on both to 120 BPM and checked them against a stopwatch. I was expecting every two beats to fall exactly on the ‘tick’ of each second. Sure enough, Ableton Live stayed perfectly in time and Cubasis started running more quickly (so the tick of each second would gradually lag behind).

I made a quick video to demonstrate:

https://vimeo.com/91003491

It’s happening with a clean install of the latest version of Cubasis and no other apps running on a 3rd generation iPad.

All my other iPad apps which report tempo / BPM are staying in time as they should. So iElectribe, iMaschine, Rebirth and others all keep perfect BPM and I can manually sync them with Ableton Live. It’s just Cubasis that’s out.

Has anyone else noticed this? Could I be missing something?

UPDATE

I’ve narrowed the problem down a little more. It’s only when loop mode is turned on.

Leaving the track running maintains perfect sync. Turning on a short loop causes the tempo to drift. This suggests that the BPM is fine, but it’s that the loop isn’t repeating exactly on the bar mark as it should (so just a fraction before the end).

I’ve tried changing where the loop start and end markers are placed but there’s still the drifting problem. They appear to snap perfectly to the bar start and end points as they should.

This is fine for a 32 bar loop as it’s just the very end (or the very start) that’s causing a problem. With say a 4 bar loop though, the drifting’s pretty bad.

Can anyone else confirm this?