I did a Fresh install of Magento 2.3.5-p1 via Composer as well as downloaded the zip file uploaded to my host and installed ( Tried all Mathods of Installation but issue remains the same ) but still there is no add Sub Categories and Add Root Categories Under Category Option in the Admin Panel. Any Inputs ?
Firstly, don’t use the zip method for installation - Unless you’re a developer because the deployment file structure varies. Composer method is the recommended option for general distribution.
In terms of issues, you haven’t given us a lot to go on. When loading into Categories (backend), view your Inspect Element > Network tool for hits to the problem. And tell us if any other features are affected (frontend/backend).