Hi Tim.
Thanks for your reply.
I found that some of my template files had special characters messing up the synching process.
These characters were: ’, “ and ” (note these are not the same as ‘ and “) which were copied and pasted from some other files. After replacing them the plugin worked again.
So I guess this was a more general problem. Thanks for your help and this great plugin. Your FAQs also helped me a lot.