Not to stick my nose any farther in, but a 4-way switch, wired with the parallel and series throws next to each other
in the order of combos, will mute
at the "in-between" notch between those two combos. That's simple electronics.
THERE'S NO PROBLEM WITH THE 4-WAY.
THAT ANSWERS THE ORIGINAL POST, and that should have been that. Apparently it wasn't.
To maintain my cred, I will now "show my work..."
Let's look at a drawing for the two schemes:
The one on the left has the combos in the Fender order (original), the one on the right is the same tones, but in different order. This is a drawing that I drew up for someone else YEARS ago.
In the second scheme (on the right) with the series and parallel combos together, if lugs 2 & 3 have continuity in an "in-between" stop, here's what happens:
The grounded lug 2 on the left pole is has continuity with lug 3 on the left pole, which is in turn jumpered to lug 3 on the right pole.
Lug 3 on the right pole has continuity with lug 2 on the right pole, which goes to the input of the volume pot.
Connecting ground to hot in this manner MUTES the guitar.
If you wire the scheme in the (original) Fender order, you don't have the same connections made, so the guitar doesn't mute - you simply shunt one or the other of the pickups at the in-between points.
SO, the "muting effect" is a product of the ORDER in which the combos are wired on the 4-way. There's no defect in the switch. OP answered.
I don't have any idea about a PCB board or whatever that you mentioned, or how it would be integrated to the pickup selector scheme, but if you have an issue with that, it's a separate issue - an issue that's not causing the "mute" effect.
Now, just an aside...
I cannot respond to your experience
with Acme's service and support, but I HAVE bought parts from them in the past, and found their service to be exemplary. Good guys, IMHO.
It seems to me that some posters on this thread have strayed a bit down another path. They're not commenting on the OP's question, nor are they sharing their own experiences with Acme - but have instead decided to comment on their perception
of your experience, with opinon rather than personal experience. It's like they're shouting from the crowd, creating a tempest in a teapot. I must say I don't care for that.