Hello!

Please show us screenshot of your problem? Did you try to Edit dial and choose another type of preview?

Just create backup of your data before that.

What about reinstall the addon? 

Go to everhelper.me/client and login there.Check your bookmark database. Make all bookmarks as you want them to be. Then reinstall addons in Chrome and Firefox. 

Then do Download in both browsers, do changes and try sync between browsers.

Use backups on everhelper.me to keep your data on your PC in case something goes wrong.

Try to reinstall addon and try again. Save backup before you do that.

Вы также можете попробовать обновить свой браузер до версии 54-56 и попробовать на более свежей версии браузера

Можем ли мы попробовать team viewer сессию?

Android EverSync is separate Android app. We can't integrate it into Android Firefox. You can use Firefox to open EverSync links, but you should open EverSync app first.

ещё не исправили

What do you mean? Do you use EverSync for Android? Android version is not connected with Firefox Android browser.