"Building is disabled: Parsing the .pro file" even though parsing has finished

After building the latest 4.6 to try to reproduce get a reasonable stack trace for QTCREATORBUG-20199, I've run into an issue where I can't run my application. In this case it's an auto test from qtquickcontrols2.git. The run/debug/build controls are all disabled:

Hovering over them gives me a tooltip that says "Building qtquickcontrols2 is disabled: Parsing the .pro file", even though parsing has already finished.

Usually (when I've run into similar issues previously) I can touch the .pro, save it and Creator fixes itself, but that doesn't work now.

Making another project active and then switching back to the original one fixes it.