Thanks for the tips.
I did delete my initial synology plex server and set up a new one on the i7 laptop. So I only have one plex server running, one HDHomerun DVR and so on.
I’ll keep experimenting to see if I can find some rhyme or reason. I just turned on detect chapters and create thumbnails to see if I can force plex to rescan the files.
I am experimenting on different networks (abc vs fox etc) to see if I can find any patterns. It is just surprising to me that even on some shows that have chapters clearly marked as commercials are being ignored on playback in other words the still play. If I press down arrow on the roku it shows chapters labeled “commercial” and I can manually move the cursor to the next chapter.
