Thanks for the help, but i think I have done all that...
To your points:
1) BiaB (2017) is directly on my computer, as it was for all versions since 2007, no change here. I have only set 2016 on a hard drive to see where the differences are.
2) I run BiaB and RB as an administrator.
3) I have found DXiplugin (configuration file) and copied there what I found in the same file from 2016 (with forte).
4) Just the same, i have checked the dxplugexclude file, and it does not include Forte.
Random thought: I have copied the content of DXi plugin 2016 into 2017 and I dont get Forte as the default synth in the first place (that is when I open BiaB and Options/Midi settings) and scanning for a new synth under "default synth" does not bring anything...
Reason why I am a bit puzzled...
My only solution at the moment is to open BiaB 2016 and everything works properly...