Hi @SBerendsen,
I don’t have a file with .940 extensions.
So I made another test to save only .jpg files from one library to another library. Please take the following screenshot for a reference.
Use a Condition to check if the Filename with extension contains .jpg, if yes, get metadata, get file content, then save the .jpg file to another document library.
It works fine, only files that with .jpg extension can be saved to another library.

Please take a try with it on your side.
Best regards,
Mabel Mao