Issue reported by: 0x8f:
If multiple machines re-use the same fluid input hatch (possibly output hatch too - haven't looked at this) but expect a different fluid from this hatch, the main multiblock machine phantoms itself on starting processing.
Example - make 2 biorefeneries, leftmost input hatch takes ethanol while the rightmost one takes plant oil (or vice versa, I don't remember but it doesn't matter). Build them in a way that one biorefinery input hatch is also the input hatch for the second biorefinery other fluid, start processing.
Multiple multiblocks machines that use the same fluid and reuse input/output hatches work perfectly fine otherwise