That example in your Tweet was very helpful. Turns out the problem was with the new Steam Input Bindings. Somehow they had all gotten reset for the UE4 editor so nothing was assigned to any of the bindings. I was able to get input working again, although everything is very messed up so I’ll have to play around with it 
Thanks again!
EDIT: Looks like this is not as intuitive as I thought. Could you shed any light on where the Controller Input Bindings in SteamVR gets the input names? It seems to be very confused. Adding inputs to Project Settings -> Input in the Sunrock project doesn’t work. I got the new inputs to show up once, but now they’ve disappeared again and won’t return. It currently just shows an older version of the bindings. I know that there is an issue with using Controller Input Bindings with older versions of UE4.