trying to open a MOV getting "File won't open" message?

[JcRvs]

Hi
I'm just trying to open a mov in losslesscut. It opened last week, but trying the same file just gets me a "File won't open" message with no extra info. Lossless cut won't open any mov files, including one that i made using lossless cut! It will open mp4 etc. I've tried deleting and re-downloading lossless but but it makes no difference. I've been downloading the manual option from github,
I'm using ios sonoma 14.6 on an apple M3 chip
any ideas to try?

Thanks!