Hi. I installed the latest version, 1.5.658.56 (Stable channel) (32-bit), yesterday. Ever since, every website keeps eventually giving me a popup over and over again:
TIRE: Could not save sync data!
EDIT: Also, everything works fine in Chrome, latest Beta version.
Have you tried disabling all extensions? You can turn them back on then (one by one) to see which one is causing trouble (if it is an extension issue). That's my guess, extension issues are common reasons for such occurrences...
I tried removing all extensions and was still having the issue. Chome still working well, even with all extensions on.
That might be a problem related to your profile then. You can try installing another instance of Vivaldi (as a standalone app) to see if the issue occurs there (or perform a full reset of Vivaldi) - and if that one works correctly, you should probably try refreshing your profile, remembering to always make a backup first.