Yes, I look at this bug since 7.2.2.4000. Nobody says something about this. This seems annoying. I starts thinking to migrate to Chrome.
https://forum.maxthon.com/index.php?/topic/28678-synchronization-does-not-work/
Hmm, there is no answers.
I think it's all about versions. Maxton`s guys stops synchronization for old versions. I tried version 7.2.2.4000, sync works.