Hm. Serious USB-C cables have some electronics in them which are supposed to communicate their power capabilities to the devices. Wikipedia says this:





My guess is that all of the A-to-C cables you've been using are the "minimal" cables mentioned in that quote, and your C-to-C cables have the E-Marker chips. The minimal cables require no special interpretation by the devices and just work (at 3A or less), but then the devices balk when confronted with the E-Marker chip, possibly disliking what it tells them (or maybe just rejecting any cable with an E-Marker at all). Alternatively, maybe the cables are communicating good information, but the specific troublesome devices are misinterpreting that information due to some kind of bug.

Related: I recently saw this video which describes one interesting special case where the E-marker chip might cause a problem. The spec doesn't allow for multiple daisy-chained cables to communicate their capabilities downstream, so if you use a USB-C extension cable, the device that's drawing the power might, in some situations, draw more current than the second-in-line cable can handle.