Alternative solution to the Dictionary sync issue
If you're having trouble syncing the learned words with your new phone/after reset. Try this.
It will help you add the sync words into your phone/google's personal dictionary. But predictions still might not work.
- Go to data.swiftkey.com to view your data and export it.
- Extract the archive and open the sync_words.json file present in the services folder.
- Use any Json to Text converter and paste the list of words in a txt file.
- Use User Dictionary Manager (UDM on playstore) to import the words from the text file into your dictionary