Yep, that was what caught me out. Took awhile to work out the interaction between the BI settings and docker flags (i.e. what in reality the VISION-DETECTION flag was all about). Thanks to all that responded.
Latest docker version of Deepstack GPU as well as latest BI (5.5.9.3).
OK, so I think I have worked out what is going on -> User error!
I was running the default docker run command (i.e. docker run -e VISION-DETECTION=True -v /mnt/user/appdata/deepstack-gpu:/datastore -v...
So I have been using an Nvidia GT 1030 for Deepstack with the "general" model for a few weeks and it has been great. Fast and accurate but very memory hungry using ~95% of the card's 2GB.
Yesterday, I swapped the 1030 for a new Nvidia T400 - also 2GB memory - and now deepstack refuses to start...