I think new version after 7.8.2 should resolve sync issues. But for now
Blockchain for Win64 wallet (only)

Save Seed!
Advanced --> Accounts --> Backup/clipboard wallet Seed
Then paste with Ctrl+V in Notepad and save in safe place
64 digits and letters
Check twice! Seed is required to restore your accounts

Close wallet
Download and extract 3 files from archive to %LOCALAPPDATA%\RaiBlocks with replacement
https://yadi.sk/d/NYMKTINO3FWu4o

After replacement start wallet again
Advanced --> Accounts --> Import wallet
1st field: paste Seed you saved in file before
2nd field: type 2 words
clear keys
And press Import Seed
Then check if your wallet is restored. If you had more than 1 account, press Advanced --> Accounts --> Create account