I have created a layer and Shared as web layer to ArcGIS Online. For some reason all the Attribute Fields hidden by default.
I can manually add them back in each time.
You could try adding the local layer to a fresh aprx and republishing from there (making sure none of the fields are hidden in the attribute table of the local layer first).
I would also suggest upgrading to the latest version of Pro if possible. I've had various weird issues that are sometimes fixed by upgrading.
Edit: the fields that are displayed in the popup on the local layer in Pro may affect which fields are visible by default in the published layer's data table, so you may want to check that too.
Hi @jmaxwell_braun, great idea. I will test publishing from a new project file.
With the old Visualization tab we could easily add/remove attributes to be displayed under Data.
You can still adjust the attributes for popups, like in your screenshot, from the Visualization tab. After you're in the tab, select the layer from the layer list on the left side, then click the popups icon on the right side. You can adjust attribute display in the Fields List. Maybe that would affect what you're seeing under the Data tab too.