And what publish mode are you using? Selection / Views or Categories? When you refer to the detail level(s), are these the settings on the connector or the Revit detail level settings? Rebar is a bit of a tricky one by nature of the API hence all the questions
And what is the detail level of the active view from which you are making the selection (in Revit, not the connector setting)?
If it is set to fine and the rebar is displayed volumetrically in the active viewport, I’d need to dig a bit deeper. I’ll send you a DM with a link to GDrive folder to put the file for debugging if you don’t mind?
I can’t reproduce the issue. Can you please try publishing the same model after reopening the model. I think some caching is causing this issue if you didn’t have the setting enabled in the first try.