what constitues user gesture
Here is the list of events that can trigger "by user activation" as defined by the specs:
- change
- click
- contextmenu
- dblclick
- mouseup
- pointerup
- reset
- submit
- touchend
This is what your error message refers to when they say "a user gesture".
mouseenter is not part of this list.
Most likely, when it worked, it was because one of those event did happen less than a few ms before (IIRC it's 50ms in Chrome currently).