2 answers
Hi,
Check if you have any record type, if yes then check if it is enabled for that recordtype or not.Or you can check under the field dependencies(if the pick-list field is a "Dependent Field" ). and enable it from there.Go to Setup>Object Manager>Object>Field Relationships>Field Dependencies(on top right of page)Check there if it is included in the values or not.Please mark it as best answer if this helps.ThanksArun