Hi,
To disable the bulk loader:
Open the aircraft customization menu -> click on the door named 'main cargo door' (it is on the left side if i remember correctly) -> choose 'no door at this position'
Alternatively you can set the loader for this particular door to be a standard, small, belt baggage loader which will stop it from clipping with the large container loader. It is done through the same menu and dropdown.
Kind regards,
Marcin Kwiatkowski