Read and Write no longer getting called in C# grasshopper component

I updated to the latest stable grasshopper and rhino nuget packages (7.3.21039.11201) and also installed latest Rhino7 installation today. I have a c# grasshopper plugin with one component inherited from GH_Component that overrides the Read and Write routines to store custom information. This stopped working after my updates, and in debug tracing I’m seeing that neither the Read or Write overrides are getting called at all on grasshopper document file open or file save operations.

Anyone else seeing this?