my Delete key does not work in Dynamo 2.12 and Revit 2022.1
Assuming this isn’t a typo… Revit 2022.1 is a beta build at this time - please provide the feedback to the Revit beta team via the beta portal where you got the download, so that it can be accounted for prior to the actual release. As of this posting 2022.0.1 is the latest Revit release, and utilizes Dynamo 2.10.
This also sounds like the bug that was present in the early R2020 days. If you have the P&ID add in installed try removing that .addin file for a session and see if that solves it.