Thanks Dave.
Rob, ASCOM applications are "mostly" 32-bits, more info in the first paragraph
here. Basically it is not possible to mix 64 and 32-bit ASCOM applications. However, this driver was compiled specifically for 32-bit. I have recompiled a new one with "any CPU" option which should cover both, not sure if it will change anything. It is in the TEMPerHum public folder.
Sorry for the lack of progress and slow replies, I got sidetracked by work. Did not have time to get testers on the SGP forums or to release the source yet