Thumbgen "Cannot Render"

I am trying to re-create all my movie sheets from the thumbgen metadata file (.tgmd) but get an error on about 60% of them.

It says [Cannot render] and a few says [Missing metadata].

Can anyone give me some advice on how to fix this?

I am running version 1.2.10.0 of thumbgen.

Thanks.

probably the TGMD file is incomplete or bugged,

run the same movie through thumbgen the old fashioned way and overwrite the TGMD file

It seems like the file is bugged - I changed the file extension to .zip and tried to open with winrar. It says file is corrupt.

I am just curios why so many of them are corrupt - out of 143 files about 85 of them were giving me errors?
It sort of defeats the purpose of generating the .tgmd file.