I cannot build vertical ducts by hand, only horizontal works. So turns and junctions doesn't work either.
Ghost build can build ducts upward, but only force ghost can build downward.
Tried with both version 1.0.4 with Factorio 2.0 and version 1.1.2 with Factorio 2.1.

Fixed in v1.1.3

Thanks for the quick fix. Could you please release a 2.0 version as well?

Done

Thank you very much :)
Wait, not good, it depends on the 2.1 version of Fluid Must Grid, 1.1.0 instead of 1.0.6

Done