I have been in touch with Ancestry again and they asked me to produce a Synch Error Report and send it to them to allow their developers to look into it further.\
This is how you do it,...when the error message appears advising tree wont synch, press SHIFT + 1 on the keyboard and you will be asked to create an error report. When its done, it appears as a zip file .
Send this to Ancestry with the request that they ask their developers to look into the problem.
If we all do this, they will have to do something.