I was rather taken aback to find my HDR-2000T doing a firmware update after I switched it off last night (clue: the LED was alternately flashing blue and red). There had been no on-screen warning message while I had been using it to watch a recording. When I switched back on, the download of Ver.1.01.20 dated 8 January 2018 was in progress (via the internet I think); although the screen indicated that version was already installed (an earlier failed upgrade, perhaps?). After restarting, all seemed well; although it took several tries and power on/off cycles before I could access the Humax Portal for the BBC iPlayer.
The mystery deepens, as this page still indicates that Ver.1.01.18 is being re-broadcast this week.