That was definitely not the correct procedure for handling an unmountable disk. The correct procedure is documented here the online documentation accessible via the Manual link at the bottom of the Unraid GUI. In addition every forum page has a DOCS link at the top and a Documentation link at the bottom.
Was the disk ever showing as disabled' (i.e. had a red 'x') ? When you say you 'formatted' disk 3 do you mean you did it using something like Unassigned Devices or from the array level. If the latter you probably formatted the 'emulated' drive, not the physical one, and the rebuild is putting that onto the physical disk.
You should post your system's diagnostics zip file in your next post in this thread to get more informed feedback. It is always a good idea to post this if your question might involve us seeing how you have things set up or to look at recent logs.