Update now problem
More info (a reply to myself!):
The latest request to update showed no increase in the percentage but suddenly requested a reboot. I rebooted. This resulted in me being informed that an update was required, so I initiated an update (once more). This time the percentage showed a steady increase - the very first time I've seen this!
So maybe there's progress here. It's just a pity that I end up feeling like a beta-tester guinea pig. Version 2019 should have been released closer to the end of 2018 when the internal team of beta testers had signed off the new product. I am renaming this product "Bitdefender Total Time-waster". My hope, of course, is that it does actually defend my system against the threats that are out there.0
It was a known issue and was fixed. Everything should update fine now.0