Hi René,
Thanks for reaching out to us on this time of trouble.
You issue seems to be related to a server problem because it’s related to the PHP function ob_get_clean() not returning the correct output, which tends to happen when your server runs out of memory for some reason.
Can you talk to your hosting service and ask if they can make your Memory Limit a bit higher?
Just to double check, have you tried to do everything on the Testing for Conflicts page? If you didn’t please do, because I did some testing and this doesn’t seem to happen on any of the servers I have here.
If that doesn’t solve your issue come back here and I will try to help you further.
My Best Regards,