Compact 1x1 loaders that use electricity. They are able to use separate filters on each belt lane, and can stack items on belts if stack inserters are available.
Yeah. That is a game engine thing. It may be worth an enhancement request to ask that in addition to Read Transfers, loaders also be granted a Read Contents (hold) of the integrated belt.
As a work around, you can read the contents of an attached belt and select Hold (all betls). The image has an example.
