Hi Bazza,
Thank you very much for the question and I am very sorry about the experience!
I believe this happens only with a certain file? Or can it be reproducible on a brand new file?
We haven't got any similar cases in our system. If this problem is file-specific, could you share with us the file for further investigation? Please let me know if you need a secure place to upload it.
Looking forward to hearing from you!
Best regards
Minh
Minh Nguyen
Technical Support Engineer
GRAPHISOFT