numbers file format 'invalid' osx 15.0.1

I have a numbers document that fails to open - relocated an older version of the file through time machine opened fine spent ages working on it, two weeks later does the same thing again. I even saved it in two location neither of which work now.

I also have a secure folder (bank details) which has started to not open and have to do the same thing use time machine to find an older version.

it is to do with the drive optimisation in OSX never had a problem before. OSX 15

it is very annoying for something that has been rock solid for 15 + years.