I use Opera-beta v41.x/64bit on Fedora-23/64bit with the XFCE desktop.
I use 2FA authentication for may websites, and opt to "trust" them on Opera-beta (on a home laptop).
Sadly, across reboots of Fedora and/or after an update of Opera-beta (i.e. "dnf -y update opera-beta"), these trusts are not preserved, forcing me to re-authentic and re-trust all of them (which is very painful).
I tried the same with Firefox, and there is no issue there. I believe a hint may come from a XFCE keyring "enter-password dialog" box that pops up when I start Opera-beta after a reboot and/or after an update. It says that "the keychain wasn't automatically opened for Opera, and to enter it's password". That may or may not be a red-herring, but mentioning it just in case. With Firefox, this dialogue does not pop up.
As far as this issues goes in my Windows 10 environment (I have a dual-boot machine), this isn't a problem. Opera-beta preserves trusts... at least across reboots (just tried that).
So maybe it has to do with where/how these trusts are stored on Fedora with XFCE and Opera-beta.
Thank you in advance! =:)