HostedAudioDevice Playhead stuck

When trying to run ProcessBlock() on a HostedAudioDeviceInterface, I find that my transport stays stuck/jitters, similarly to issues caused by normal audio devices.

I noticed that in HostedAudioDeviceType::processBlock(), there are no devices in the list, and I wonder if this is related. This seems to be the code relevant to the audio processing, since the Fifo stuff is for MIDI (my plugin doesn’t use MIDI). I saw a device etting added during HostedAudioDeviceInterface::initialise() (tracktion_HostedAudioDevice.cpp:305) but there are none by the time I get to processBlock() (seems like it might get wiped on the next line when the device manager is initialized).

I think I followed the example in the tracktion repo for the HostedAudioDeviceInterface pretty closely, but still having this issue. Any ideas of where to look?