Tablo 4th Gen 2 tuner playback issue

A bandwidth issue would also be my guess, but it's only a guess.  Is your Tablo using a wired connection?

I have an old Premiere (3920) with very poor Wi-Fi reception and when I used it with a 2-tuner Tablo (that I later gifted to my mother) it didn't work well.  I just got the 4-tuner model, but I haven't had a chance to test it.  I don't know if I'll swap it with my mother's or keep it for myself.  I've noticed that the 2-tuner one sometimes struggles with live streams at my mother's, but the Tablo and her Roku are both connected via Wi-Fi.  I'd like to get one or the other wired to see if it helps, but it won't be easy to do.

I noticed something interesting last night when I was at her house and she was watching something live and the Tablo app crashed completely.  I went back into the app and selected the same show, but set it to record.  I was surprised when I was able to rewind to before the point where I started the recording and could watch right through the spot where it crashed without anything missing.

You'll see similar complaints about live streams from people using HDHomeRun tuners (which I also have).  In that case, I've always felt that it's the glitches in the stream caused by RF reception issues that trip up Roku devices.