How to cleanup AEMixerModule after stopping AEAudioUnitOutput?

[runeb]

I have an audio controller that has these properties

  self.renderer = [AERenderer new];
  self.output = [[AEAudioUnitOutput alloc] initWithRenderer:self.renderer];
  self.mixer = [[AEMixerModule alloc] initWithRenderer:self.renderer];

Playing audio consists of adding AEAudioFilePlayerModule objects to the mixer, with different starting timestamps.

// For every sample
AEAudioFilePlayerModule *fp = [[AEAudioFilePlayerModule alloc] initWithRenderer:self.renderer URL:sample error:nil];
// Calculate timestamp
[fp playAtTime:timestamp];
__weak AEAudioFilePlayerModule *weakFp = fp;
[fp setCompletionBlock:^{
  [self.mixer removeModule:weakFp];
}];
[self.mixer addModule:fp];

And then starting playback is simply

[self.output start:error];

While audio is playing, more AEAudioFilePlayerModule might be scheduled.

Stopping audio is done like this:

[self.output stop];
[self.mixer setModules:@[]];

With this setup I can play and stop audio fine. But after playing, stopping and then playing again I get these messages in my console:

0x6000000ef280: AEManagedValueServiceReleaseQueue called from outside realtime thread
AEManagedValueCommitPendingUpdates called from outside realtime thread
0x6000000ef200: AEManagedValueServiceReleaseQueue called from outside realtime thread
0x6000000edc80: AEManagedValueServiceReleaseQueue called from outside realtime thread
0x6000000ef800: AEManagedValueServiceReleaseQueue called from outside realtime thread
0x6000000ef280: AEManagedValueServiceReleaseQueue called from outside realtime thread
AEManagedValueCommitPendingUpdates called from outside realtime thread
0x6000000ef200: AEManagedValueServiceReleaseQueue called from outside realtime thread
0x6000000edc80: AEManagedValueServiceReleaseQueue called from outside realtime thread
2016-09-28 23:57:51.516 TCH[55016:17181235] TAAE: Suppressing some messages
0x6000000ef280: AEManagedValueServiceReleaseQueue called from outside realtime thread
AEManagedValueCommitPendingUpdates called from outside realtime thread
0x6000000ef800: AEManagedValueServiceReleaseQueue called from outside realtime thread
0x6000000ef200: AEManagedValueServiceReleaseQueue called from outside realtime thread
0x6000000edc80: AEManagedValueServiceReleaseQueue called from outside realtime thread
0x6000000ef800: AEManagedValueServiceReleaseQueue called from outside realtime thread
0x6080000f2000: AEManagedValueServiceReleaseQueue called from outside realtime thread
0x6000000ef280: AEManagedValueServiceReleaseQueue called from outside realtime thread
AEManagedValueCommitPendingUpdates called from outside realtime thread
2016-09-28 23:57:52.596 TCH[55016:17181253] TAAE: Suppressing some messages

Sometimes the app crashes because of this. So the question is what am I doing wrong and what is the proper way to clean up after stopping audio in this case?