I am having the same problem, but I suspect my problem is crappy/counterfeit japan verbatim discs from ebay.
VERBAT-IMd-100 6x BD-R DL 50gb media
1.00-06 speedpatched firmware currently (about to upgrade to 1.00-07 or -09 to see if it helps)
The discs are not recognized when inserted. I can eject and load a bunch of times and some times they work and sometimes not. I'm in the middle of a verifying a disc from one of the instances where it loaded the disc, and even re-loaded it allow the verify in imgburn.
RITEK BD-R SL 8x RITEK-BR2-00 discs load just fine