However, it does not update the toggle. Opaque can be achieved again by pressing the toggle twice. Only happens once - once it is fixed after observing the issue, it will not happen again for the same part.

Take your time of course. This is a minor annoyance anyway with an easy workaround, so I'd say pretty much everything is higher priority

One liner apparently; I wasn't properly resetting opacity status on texture change.

Fixed in dev; available shortly.

Fun...
Likely related to unity's retarded material vs. sharedMaterial setup.
Going to take a bit to get this one tracked down and fixed due to that.