OK, I'm sure this is a fluke... but the Dio.8 card is recognized now. If it's reliable will turn out, but here's the only thing I changed (which should not be related, but somehow it works now):
I had trouble syncing to an external source (for now, and M-Audio Octane ADAT preamp). Only the internal sync via the Apogee Clock card would stay locked.
I ordered a BNC "T" piece and a Terminator, to make sure that the Octane's Word Clock Out port is properly terminated (and if not, connecting the Terminator would fix that). This finally arrived today.
So, I connected the T-Piece to the M-Audio Octane's Word Clock Out, the Word Clock cable going to the d8b's Apogee Clock card on one side of the T, and a 75 Ohm Terminator on the other side of the T.
Not only does the d8b now sync to external clock, it also recognized the Tape 1-8 card. Time will tell if this really fixed it, or was just a fluke. Otherwise "Twilight-Zone" style component interaction