AUv3 plugins again and again stop producing audio output


When using two or more instances of audio units, they stop producing audio output. Sometimes this happens every few seconds.

Expected Result
When using two or more instances of audio units, it should be possible to use them without issues.

Actual Result
When using two or more instances of audio units, it is required to quit Cubasis 3 every few seconds and after that to launch it again, since the audio units stop producing audio output. This doesn’t happen when using the same audio units with other hosts.

AUv3 plugin “SoundFonts” Version 2.24.4, update 1 month ago
AUv3 plugin “BeatHawk” Version 2.2.15, update 6 month ago
Host “Cubasis 3” Version 3.4.3, update 2 month ago
iPad Pro (12.9-inch) (3rd generation) MTFR2FD/A
iPadOS 15.5 (19F77)
Using the iPad’s audio device, not tested against a connected USB audio device.


I was mistaken, it seems to happen with other DAWs, too.

Seemingly using AUv3 Foo synth is ok.

It seems to be ok, too, using AUv3 Foo synth and on another track AUv3 Bar synth.

Issues seem to happen when one track does use one instances of AUv3 Foo synth and another track does use a second instance of AUv3 Foo synth.

I can’t say for sure, for now it’s just a guess.

MTS suffers from similar effects as Cubasis 3 does.

Auri Pro might suffer from this, too, but actually Auria Pro is that broken, that there are probably other culprits responsible for its issues.

I will try to use MTS or Cubasis 3 with just one instance per AUv3 synth. If it should work, I can stand it as a temporary workaround, as long as several instances of the same AUv3 EQ or compressor shouldn’t cause the same issue as the AUv3 synth seemingly do.

Hi @unknown_crewman,

I’d suggest to get in touch with the 3rd party app vendor and let them know about the issue.
If required, we’re at had to have them equipped with a Cubasis 3 promo code for testing purposes.

Please keep me updated!



I reported the issue against Beat Hawk upstream and SoundFonts upstream. I made several additional tests. Note, only BeatHawk fails to work on MultitrackStudio, too. SoundFonts fails only, if the host is Cubasis 3. SoundFonts does use the GitHub issue tracker.