After some further digging here’s what we found:
From: Roku Tablo 4th Gen App Update (v. 0.8.700 and 0.8.701)
Part of the stability changes for the live TV grid include limiting some low-end Roku devices running Roku OS 13+ to displaying 7 days of data, instead of the full two weeks. These devices do not have enough active memory to load the full live TV grid.
Hope this clarifies.