SW 2017 SP5.0

So I am designing an assembly and need some extruded cuts in select parts so other parts can fit through them.

Sounds easy - extrude a cut at the assembly level, propagate feature to part and then select the parts that need the cut.

Well Solidworks 2017 certainly has huge problems with this feature, but this is a new one for me.

Design is finalized and I made a solid that will be made from sheet metal into a sheet metal part.

Then I tried to do a flow simulation, but kept getting zero flow in one of my subdomains and warnings about the missing flow conditions.

I deleted my fluid subdomain and when I went to recreate it, It was chopped short.

Turns out the extruded cut only propagated to a few of the selected components.

So I do what I have to do every time I open the file again - uncheck and then recheck propagate to parts. This time it told me that I can't propagate a feature to parts in assemblies with multiple instances of sheet metal parts!

FWIW, the extrude does NOT go through the sheet metal part, but it does use an edge of the sheet metal part to define the sketch for the cut.

But even if it did, using the sheet metal feature breaks Solidworks normal function?!?! At least even more than SW does by themselves.

We are about to switch to SW2018. Please tell me that the assembly-level extruded cut propagate to feature works in SW2018. Pretty please?

So it looks like I have to make part level cuts in all the parts with sketches w/external links. But I don't trust SW to not give me the same error at the part level.

Or it looks like I have to make dummy parts that I can make into sheet metal that aren't in the assembly. But how do I link the dummy parts to the "real" parts that are in the assembly.

Really, Solidowrks?!?! Nobody ever builds an assembly that incorporates sheet metal parts?