No, we did not open a ticket. The inconvenience is minor and we are forgiving! But here's a bit more background for anyone interested.
New theory: we must consider Roku's remote control. Last night, while using Tablo/Roku 4 to merrily skip some commercials (pardon the split infinitive), upon initiating the slowest FF with the Roku remote, the screen simply froze with the FF progress bar progressing nowhere. This behavior has manifested, only on Tablo, every night for the last week or so.
So, we switched to Netflix for a couple of minutes to watch a slow train make its way from Bergen to Oslo. . .
. . .then we switched back to Tablo and avoided the regular, remote control even though it got us on and off the train without incident. We used the Roku iOS App instead. Using the iOS controller, we had no problem for the rest of our evening Tablo sessions.
Roku has a history of glitching remote controllers and power supplies, so one needs to include those while troubleshooting.
I don't have a complaint. As long as our 4-tuner Tablo successfully tunes, records and we can find a way to play the files, we're happy.