Currently the Paint Formatter icon (a paint roller) is only visible when the formatting bar is visible. The formatting bar is only visible when an object is selected. This creates an issue when the Paint Formatter option is set and no item is selected.
In order to deactivate the Paint Formatter an object must first be selected. If an object of the same type but with different formatting is selected, there is the unwanted effect of immediately applying the locked format settings (the action of the Paint Formatter) to the selected object.
Once the Paint Formatter is turned off the unwanted application of those settings must be undone.
If the Paint Formatter icon (or even the formatting bar) remained visible when no object was selected then it would be possible to prevent the application of the locked format settings to that object.