Thanks for the investigation, the update on the likely cause and the upcoming fix!
3.2.15 is out with the fix!
Hi. I tried 3.2.15 with my old legacy tuner late yesterday.
I am happy to report that, so far, the tuning/playback issue (apparently introduced in 3.2.14) appears to be gone. It is great that I no longer need to try multiple times to tune a channel/program!
Also, maybe it is unrelated to the changes made to address the tuning/playback issue but: It seems to me that the PQ is somewhat better than before. Could this be related to UDP packets being processed "better" upon receipt by the ATV-device/Channels-app? Maybe it is just my imagination...
Finally: I received my EXTEND tuner and will be adding it to my home network shortly.
Thank you again for this fix!