Long hang on deconstructor while stopping transport sources

I have a DLL that is being hosted by another application. (not a DAW plugin)

The DLL is effective a mixerAudioSource that is being fed TransportAudioSources

When I call the deconstructor, it all quits fine (I think everything RAII compliant and should be OK) except I get some clicking noises from the forced stop of the sources in the mixer

so I added just a small loop to find any source that isPlaying() and call a stop() prior to completing the destructor

for (int i = 0; i < inputSources.size(); i++) {
	if (inputSources.getUnchecked(i)->isPlaying())

however, this makes the deconstructor appear to hang for a second or more before completing

any thoughts?