Trying to convert AAC to MP3 but option greyed out

Michael,

Are you following the procedure in here?

https://support.apple.com/en-gb/HT204310

Note that to convert, the audio file must be local (not in the cloud) and must not be protected or Apple Music.

Michael,

Yes, to do the conversion the original AAC file must be present on the computer. To see the file, right-click the track in iTunes and choose "Show in Explorer" (or "Show in Finder").

If the file is not there, but was purchased in the past, you can download a fresh copy per this guide:

http://support.apple.com/kb/ht2519

Michael,

Does the "Kind" field say "Purchased AAC audio file"? if so, you should be able to convert it. Did you make sure the original AAC file is located on your computer? Do you have your import preferences set for MP3?