I'm attempting to do some cleanup on a simple classified raster in the Pixel Editor in ArcGIS Pro and the Current Class/New Class dialog boxes are empty.

There's no ability to 'Add a new class' as suggested in the doc. What's up? Doesn't work at 2.6, rolled back to 2.5 still no dice. Am I missing a step in the process to activate this tool? The raster property is set to Thematic. I've tried copying the tif out to a gdb, changing the bit depth, using a different dataset altogether...still nothing. I have a support ticket started with ESRI but thought I'd reach out in case there's anyone else out there that can relate.