I noticed this on a few 1.14prs, but after it’s still the case with this most recent, I figured I’d throw this out there in case you hadn’t noticed it.
Whenever I attempt to add a composite node to my graph and connect two inputs I receive the following error dialog.
I have noticed though, that if I ‘rebuild’ (F5) many times (similar to your advice on loops), it seems to eventually work. I first noticed that I could get it to work at all by switching the Output dimension property to Largest surface, but then later noticed the F5s seemed to do the trick as well.