A serious compatibility issue between 8.0 and 8.5 designer

This is so bizarre that I have spent days making sure I’m not making a stupid error, but it’s too consistent.

I have two machines - one running R801, the other R851. I need to maintain two versions of the same design database, so I work on R801, updating code on both databases. Everything is fine there. BUT … on R851, any changes I made on the 851 database do not appear in designer. The libraries are not changing, even though the dates show the latest updates made on 801. I can even delete my libraries, and cut-paste from the 801 version, but I still see the old code. Now for the really wierd part!!! The code runs correctly on 851 - all the changes I made are in effect (I am logging). So this is a pure designer issue

Can anyone out there (Andre maybe) please tell me I;m not going mad.