@jslattery tried to solve the problem for about 3 days didnt manage to do so, not even complete reinstall helped. I straight up gave up and started to use "Notebook" by Zoho extension instead. It is a rather useful alternative and sync is without problem.
If you decide to go the same way, note that it does not come in Opera store by default, you have to get it from google chrome web store. Luckily that is possible now even without the Chrome Extensions addon.