I’m having this issue too and I’m afraid that it might be a bug in 4.22. I tried doing the same thing in 4.20 and it displays normally.
Edit: Looks like the bug is already being tracked and is targeted to be fixed in the next engine update. Fingers crossed!
Edit 2: Doing some more search, it seems like they’re doing a curve editor revamp in 4.23. Interesting. Trello