it seems, that I'm not only one with this problem. In slovenian community there are some users, who use Alva BC6 displays and after updating NVDA from 2016.1 to newer version, displays have stopped working, and when we chose Alva BC6 from braille settings, NVDA said "could not load alva bc6 display" Downgrade was not a solution. it means, that this problem exists for all versions of BC6 series and on all OS.
please, please help, if you have any solution for this problem.
p.s. BTW NVDA does not use a latest BC6 driver.
p.s.2. is there any chanse that will VFO group (Optelec devision) develop customised drivers for NVDA for their products?