Just to clarify my previous post:
Setting "Stop previous broadcasted service on return to movie list" to 'No' allows Timeshift to start when I stop playing a recording. So far, so good.
However, once I pause or rewind within the Timeshift and then eventually press 'Stop' to return to present time, I can no longer use (pause or rewind) the Timeshift again, unless I change channel. This limits the usefulness of Timeshift as an one off attempt, but there's worse:
I cannot press FWD or press 1,3,5 to jump forward. On each occasion I return to current time at the end of the Timeshift, at which point I can no longer rewind as I explain above.
This problem started after release 6.7.005 or thereabouts and only manifests after playing back a recording and stopping to watch TV. Otherwise, the Timeshift function works as expected and I can pause/RWD/FWD and jump back & forth, as long as I have not played a recording while in the same TV channel.
Please let me know if there's any more information you need from me, or how I could troubleshoot this further.