Hello I don't know if this a problem from the mod or the base game here is the situation.

I have built a refinery, I connected pipes from the output of the refinery to my liquid bus and then added a ghost of a future oil refinery and added ghost pipes to prepare for its future outputs. These ghost pipes are in between the first refinery and the liquid bus. When the ghost pipes are there the output of the first refinery does not flow. When I remove the ghost pipes the output flows normally.

If it's not caused by the mod or you don't see this message I will also post it on the main game forums.

Cheers

Seems more a vanilla bug, but for be sure, can u provide some screenshot? The situation is not completly clear to me

Hello I asked the devs, it is an intended feature of Vanilla to avoid fluid mixing during blueprint construction, sorry for the scare.

Have a good day