Hmmmkay, might not be a win 32 bit problem. Finding now that some tools that are unnamed because it does not engender Vogon friendly discussion may produce mkv files that are poorly indexed, resulting in players being unable to seek within them. Guess I have to reprocess this file to behave better in a mixed player environment. Testing it now with an Android client that is fairly up to date and that won't seek in it either.

edit: Heh "Marty we have to go back!" ... now it's like using an old school betamax that didn't disengage play head for fast forward, so gotta squlilaibalellibibillilibilillibiasqiowippllip do max ffwd in play mode.

editII: It dropped out of that too. Tried converting it over lunch with Media Espresso and it produced an mp4 that cuts off in the same place, so multiple problems with that file and I will give up on it I think.

If the index is bad simply running it through mkvmerge will likely fix it.

Thanks jmarsh.

This is the wrap up, Windows 7 32bit did not have an innate problem sharing that file, all 5GB of it are readable over the network. Several utilities including mkvmerge were tried on it to fix it. The final conclusion is though, that that file only contains data matching the 1:11 run length experienced, and the remaining 30 mins or so is not there. This confirmed by multiple fixit solutions only producing a 1:11 length file, whether by reindexing, removing everything but the second half etc. The file bitrate is ~10,108 kbps, which played for one hour 11 mins is around 5 GB so that's all there is. Damn it for making me do math 🤣 I know nothing of the history of the file, but we might assume that settings were bad, intended for 2k or 4k maybe, with a size cap for 720 or 1080 appropriate file size, due to fat fingering or typo in the interface of the tool used to produce it originally. Orrrrr... it was a partial transfer at some point and an ~8GB or so file was accidentally cut to 5GB.