Well, thanks for responding anyway.
First! Huzzah! \o/
MPEG-2? For HD content? Seems... unusual. o_O Although, probably not that unusual, considering my project...
Well, on the main screen under Menu Style, there's a "Customize..." button; clicking on that and going to the "Encoding" tab, under the "Video" section there's an option that reads "Reencoding", which I set to "Never", as I was doing the encoding externally. Even if it was ignoring that setting, I would have expected the same behavior on the first item in the project... unless this is a "bug"... errr... "undocumented feature" that it only works with the first item and not with subsequent items.
I would guess/hope not, as neither the encoded files nor the setting under "Customize..." is MPEG-2 (the one under "Customize..." says "MPEG-4 AVC", even though I have "Reencoding" set to "Never" anyway).
Well, I certainly don't necessarily expect it to be accurate to within fractions of a second, but "some" semblance of "reasonably close" should be a reasonable expectation. I wasn't aware of the "Prevent App Nap" option; have set that - will see if it makes a difference. "For the record", on my latest attempt, having taken ~3-4m to reach 68% and complete the first item, it then took almost the entire past 6 hours to reach 75% - and was still on the second item.
Selecting the poster frame from the edit window *does* work, but... it seems to defeat the purpose of having audio preview (especially with the AU filters, although I'm not using any and, although each of the 3 are set to "None" by default, I've also tried manually de-selecting the "Enabled" checkbox on each to ensure that it wouldn't even try - doesn't seem to make a difference). I've also tried going into Toast's Audio preferences, manually selecting "Built-in Output", and unchecking "Show advanced audio mastering settings". Additionally, while trying to use the "AU Filter..." button on the item, it reported all 3 effect numbers as both "Enabled" and "None" by default (seems a bit redundant). If I uncheck them all and then use "Edit..." to try to preview the track and check the "AU Filter" tab, all 3 still show as both "Enabled" and "None".
At this point, I'd have to say there are definitely some serious issues with Toast 12.1 on OS X Yosemite 10.10.3 if the interface isn't even consistent.
Thanks; I appreciate your taking the time to reply. I haven't used Toast in "ages" and, while it didn't have anywhere near these features back then (Toast 6 maybe?), I also don't recall the product having anywhere near so many issues. Hopefully a dev or support tech will actually read these, investigate the issues, and there'll be an update "Soon™".
I'm going to try a complete shutdown and reboot, log in with startup items disabled, make sure Toast is the only app running, let it go overnight, and see how far it gets. I would hate to have to go back to FCP, re-export the track with the "self-contained" option, and let Toast do all the encoding, but... if I can get a "workaround", that'll let me at least continue to make progress while waiting on a "solution".