Hi Optodata, Thanks for the suggestion. It bore fruit, but in an unexpected way.
First, why did you think it would work?
I was testing using a single 30 second clip of .MTS:
1920x1080
H.264
21.56 Mbps
29.97 fps
Audio is 48kHz, 256kpbs stereo.
That's the one that failed as I described above (after the full big project failed).
When I followed your suggestion, importing within "create disk", it worked the first time. An iso was successfully produced. However, that was with no menu.
Then I tried adding the custom menu I used for the full project (even though the clip has no chapters). Then it failed again.
Then I tried using the Cyberlink-supplied "World Monopoly" menu, unaltered. It worked. I altered the menu and saved; it worked.
I tried making a new custom menu from scratch, with no images or added buttons, only the default. It failed.
It appears that it's the custom menus. This is very strange, because this is the same custom menu that works fine in making a standard def DVD. It's only Blu-ray that fails with (apparently) any custom menu.
Any suggestions, or response from the CL gurus?
p.s. I'm going away for Christmas, so I won't be responding until after the weekend. Happy Holidays, everyone!