I had the same problem starting last week. The time was off by a few hours in the regular Roku app but fine in the beta Roku app. Rebooting the Tablo fixed it.
This issue coincided with programs scheduled to record not recording. I have sent support a ticket on that.
Also, I don’t know if its related, my guide status shows being updated 13 days ago. When I try to update it, it says downloading, and then says updated 13 days ago. Does that sound right?
2 tuner with 2.2.6
Roku Streaming Stick
Time set to CST and automatic
No VPN