No browser errors.Are there any errors in the browser console?
When you mentioned resetting to default, do you mean the editor toolbar icons? I notice a custom one there so I wonder if that's related (though I don't think it necessarily is).
removebuttonsoption on one instance can affect another instance unexpectedly.
Any changes made as a result of this issue being resolved may not be rolled out here until later.Ensure that each editor instance starts with an empty set of buttons to remove so that removals only affect the desired editor.