Strange Issue Capturing Mini-DV

Hi. Since "real" work has been slow due to COVID, I decided to tackle a personal project. I have been digitizing Mini-DV home movies (yes, technically they are already digital, just moving them onto a hard drive) and using Premiere as the capture vehicle. My goal is to simply have the full tapes on a drive that I can then duplicate, pass on to my kids, 2 of whom are now adults, and have a backup in case the tapes are someday unplayable, or decks are not tolerant of the tapes, or Firewire is no longer supported (wait, that already happened!)

I have over 100 home movie tapes, and probably twice that in backups and reels and paid projects. It's been a good exercise. First, let me say I am very impressed. I have gone through 96 tapes, and only one of them had modest dropouts. All the others were pretty flawless. Premiere has also worked well. Some tapes have control-track breaks, so a "tape" ends up being 2 or 3 (or 9) clips on the drive; but that's OK.

Here is my problem. I have 3 tapes that will not digitize, but Premiere does not stop, or warn me, or flag in any way that it's not doing its job. I'll enter a reel name, a clip name, and click on the "TAPE" button (to digitize the whole tape) The time code starts rolling and the estimated time/ drive space that's left appears, just like the other 96 tapes. But with these 3 particular tapes, with no warning from Premiere, the capture process stops after about 45 seconds. The time code freezes, but the deck continues to play, and the capture window stays up, and no pop-up window asks me to save the clip (as happens at the end of the tape or in a control-track break) I watched a full tape, one hour, and assumed it had captured, but the clip was only a couple dozen MB and 45 seconds.

The only clue I can offer is that these 3 tapes are dubs from analog originals. But so were several other tapes that digitized in full… and once it’s recorded on Mini-DV tape, it’s just ones and zeros, so the quality of the analog video should not come into play at all.

Running this on an older MacBook Pro 13”, Sierra 10.12.6, and Premiere is up to date (auto-update enabled) I’m using a Sony GVD-1000 “Clamshell” deck, mini-Firewire cable to 400, to a FW 800 adapter, to Thunderbolt 2. It’s always worked fine. Tapes digitized before and after these 3 are fine. Multiple attempts with these 3 tapes always yield the same result.

Any ideas???
Cheers