In several latest LE 10 Nightly builds I am experiencing mentioned issue while playing Live TV (DVB-T2). Currently seen on 20210312 build / RPi 4B 2 GB device.
I am using Tvheadend Server 4.2 (126.96.36.199) + Tvheadend HTSP Client (188.8.131.52), Timeshift set to use RAM only, Fit to RAM, 900MB max.RAM size.
The Timeshft data are randomly discarded and it looks it's related to error: LE tvheadend: htsp: 127.0.0.1 [ | Kodi Media Center ]: Disconnected
The issue happens most often when 1920x1080 / 50 FPS stream is played & some Timeshift offset is active. Randomly, after some time (looks always when the Timeshift buffer is full), usually when I try to seek / move the offset, it jumps to 0 offset, the Timeshift data disappears and starts from 0. Sometimes the Timeshift is disabled then (despite it's configured to start automatically) and it's necessary to push stop / start or switch between channels to get it activated again.
In past, sometimes the oom killer was activated, usually killing Tvheadend service. This does not occur now but the Timeshift data are getting cleared which is a bit annoying.