Hello. I have same problems with MyPhoneExplorer Thunderbird addon v. 0.9.9. Version before worked correctly, but in this version You can see bug on screen shot.
It was a bug in the language translation.
- Download a fresh copy of MyPhoneExplorer 1.6.4 from my Server
- Install it
- Uninstall the Addon
- try a sync, MPE should install the Addon automatically