Question, i love the fact that i can use circuits on the loaders.
But i have noticed that if i use Ultimate Belts mod and get a miniloader "from" that mod. I cant use circuits on any of them. Is that supposed to be so or is it a bug? As it is quite annoying.

From the mod description:

Ultimate Belts Caveats and Warnings
Ultimate Belts support is in BETA state.

Factorio core engine limitations restrict inserters pulling from belts to
60 items/second, or 4.5x yellow belt speed. Further, loader entities are
restricted to 120 items/second.

Miniloaders at "Ultra fast" and faster speeds use vanilla loader entities in
addition to inserters, giving a max throughput of ~180 items/second when
interacting with chests and other containers. They will not give full
throughput when loading cargo wagons, and circuit control is disabled since
vanilla loaders cannot be circuit controlled.