Martin?

Hi jet,
thanks for the detailed report and especially the follow-ups. The ~30 minute self-recovery is the key clue here.

I'm the developer of OMTake. The fact that it behaves identically on both vMix and the BHM OMT Media Player, that restarting the app or phone doesn't help, and that it clears itself after about 30 minutes all point to a discovery/registration issue rather than a port collision. When you stop the stream, OMTake isn't cleanly de-registering its OMT source, so the decoder keeps holding the now-dead entry until its cache expires — which matches your 30-minute observation exactly. Restarting the decoder clears that cache immediately, which is why that's the only thing that works.
So the fix is on my side: on stop, OMTake needs to close the connection cleanly and send a proper de-registration so decoders drop the source right away instead of waiting for the cache to time out. I'm working on it and will post here when there's a build to test.

Thanks for the precise repro, it made this much easier to track down.