Emil:
I assume you have connected the BM5 Dvi output to your BV8?
Sorry, should have given complete setup. BM5 component out to BV8 AV3. AV3 set for PC and beomaster 5 selected as the PC. Couldn't use DVI as the BV8 has only 2 HDMI (AV1 and 2) and both are in use.
Have now replaced component cable with DVI (BM5) to VGA (AV3 on BV8). Rebooted BM5 and now have BM5 display on BV8. It appears from the BS5 installation guide that component doesn't work on BV8 with BM5. It says in resolution table that for BV8 that Resolution (YpbBr) is not possible.