@Eleln It is maddening but glad you found this! Unplugging the tablet or working in Safari have been my only options so far. Wacom gave me lots of help but nothing worked. Squarespace just said what they always say "we're working on a fix for this." Drivers, updating privacy>accessibility settings, nothing worked.
Apparently this is similar to touchscreen issues they're having, but not sure if they're making any progress. Good luck!
OH MY GOODNESS I have been losing my ever loving mind with this today. I had already restarted my computer, updated both browsers, fiddled with just about every setting i could think of. Then I thought there's just no way this is me?! Bless this thread because i was ready to fling myself into the ocean in despair LOL! I had about 20 blog posts to schedule for a site and nothing was working. This is an absolutely silly issue to be encountering, but since it's the third glitch with the WACOM i've had today after an update it makes sense. If anyone finds the driver update/fix for this let me know pleas pretty please! 🙂