I'm working through the move from DP (in the midst of the current empty-DP channel fiasco), but I've run into a category issue.
I've side loaded the channel. All looks good, EXCEPT categories are not propagating. I thought that maybe the categories are added through Dashboard similar to the way that they are in DP, but there's nowhere to list them. My feed is an RSS via JW...the same that I have used since maybe 2017/18. (JSON never has worked for me from there.)
You should try the new version Channel tool to create an SDK channel with an MRSS Feed
You can try the new wizard tool that should alleviate some of the anxiety of converting a Direct Publisher channel to a SceneGraph channel or creating a new SDK channel. The tool can be found on GitHub.https://github.com/rrirower/DP2SceneGraphWizard