my revision property is blanked on save...

this has me stumped.

I have a single file, that whenever I save it, the cystom property "Revision" reverts back to a single space. as far as I can tell, it is just the one file, and just the one property.

I have tried deleting and re-creating the property, ctrl-q before save, replacing the sheet format, re-loading the sheet format...

Any Ideas?

SolidworksDrawings And Detailing