I, too, have successfully used USB-C extension cables, despite the fact that the USB-C spec doesn't allow for them. In my case, I have used them to extend the reach of the PSVR2 headset. Since that's relatively low power, compared to, say, charging a laptop off the cable, I'm probably fine. As that video explains, though, problems may occur if you attach a device which needs more power.

That's all irrelevant to Dignan's problem, of course, since he wasn't using an extension cable, but it's certainly an interesting side note, pointing out how the E-marker chip in the cables just makes life harder and more complicated.