Just fixed in 51 update, here. Every handler works fine.

same issue here, with uTorrent, Nexus Mod Manager and Mod Organizer handlers.
Opera won't save my preferences.
System double checked for viruses and malwares. Fine.
Permissions and access to drives and directories, fine.
Everything was working fine, till I installed a new system from the scratch, Windows 10 fall creators update and latest Opera.
HDD in AHCI mode (dumb me), no Intel RST runnning.
Watching this topic and posting any new info I find.