Steps to reproduce
Make a list with multiple items. Make sure some item in the list is a sub-list (i.e. make sure an item in the list has children).
Turn the list into a numbered list. Expand the sub-list.
No change to the numbering on the list.
The numbering resets to 1. after the sublist. This goes away and comes back dynamically as you expand / collapse the sublist.
Chrome, Windows 10 (I haven’t seen this in the Windows 10 app).
example of the numbering resetting: