I'm on a clean install of Forge 31.1.0, ARL 1.5-40, Quark r2.1-229 and nothing else. Config is in the default state. Log here.

I've noticed this while messing around with piston that move inventories. For some blocks comparator signals are updated on the new block position, for other not.

Updates: chest, furnace, hopper, cauldron, lectern, ...
Doesn't update: dropper, dispenser, possibly more?

OP says hoppers do update; however, when moving hoppers via the Magnet, at least, comparator output is not updating for me.

Not sure if this is better as a separate report or appended here; I'll leave it here for now unless someone advises me otherwise.