The Apple TV app does not currently support playing in-progress recordings from the beginning of said recording. This is because tvOS does not support playing video in MPEG-2 format.
It is possible to begin watching in-progress recordings (AKA 'tape delay' or 'time-shifted' recordings) with the 4th Generation Tablo via the majority of compatible Tablo apps.
Within seconds of the start of a recording, you can begin playing back an in-progress recording from the LIBRARY screen.
Playback will begin at the start of the recording via Tablo apps on Roku, Amazon Fire TV, Android TV, Samsung smart TVs, and LG smart TVs.
However, it is not possible to view in-progress recordings from the beginning of the program via Tablo apps on iOS and Android mobile devices.
This is because these apps do not use the device's built-in player software as Apple products and many Android smartphones and tablets do not support the playback of MPEG-2 video natively. For this reason, specialized player software is required.
This player software is not able to differentiate between live streams and in-progress recordings as they both do not have specific start and end points. Therefore, playback of in-progress recordings can’t be started from the beginning of the program on those devices.