It pains me to say that both crank and BB are brand new, never used, straight out of the packaging. The setup I'm swapping out is a good old square taper, so I can't test against that.
Now, here's what happens when I hammer the crank back out:
It seems that the plastic cap that acts as a spacer between the shaft and actual bearing race isn't to spec; for some reason, it's just too snug.
Now, here's how the crank fits without the plastic spacer:
The same issue isn't there on the non-drive side; the shaft didn't push the other plastic cap out with it as it worked its way through, as I thought it might.
However, here's how far the shaft went into the drive-side cup of an off-brand, Chinese BB before it stopped cold. That's a BB I had used on another bike without issue for months:
That, too, is a no-go. I measured the shaft at several places along its length and I got everything between 23.93mm and 24.01mm.
Here's the BBR60 on the shaft of a Chinese Hollowtech II knockoff:
Fits about as snugly as you might expect with the force of my hands, no issues there.
I must admit that I have no idea what I'm going to do at this point. My options are to order another BB and see if that'll fit, or talk to the LBS and see if they can help. I could order a square taper 165mm crankset and call it a day, or I could just go with Chinese parts off of Aliexpress again. We'll see.