My Tablo on my Roku TV worked fine, however both the Tablo Apps on my living Room and Bedroom Roku devices worked fine, except when you went to the “Live TV”, it would eject you right back out to the main Roku App. This went on for about a week, and now seems to be working ok.
Try this look at Tablo Settings>Troubleshooting>Audio Compatibility Mode and toggle it to on. This is I known issue with certain Roku versions. This may help, if not then call Tablo support,
https://support.tablotv.com/hc/en-us/articles/32495759693972-Enabling-Audio-Compatibility-Mode-for-Roku-on-the-4th-Generation-Tablo