Unable to find an existing custom field in Jira Admin Custom Fields section

[Koushik Kadambala]

A Custom field shows up in Jira project, configuration and its screens however I'm unable to find it in Jira Admin custom fields menu and also in automation. Here are some snips. 
(I want to let you know that we have migrated to Jira Cloud from a Server version.)
How do I solve this please ?

[Gary Spross · Accepted solution]

The "Affects versions" & "Fix versions" are system fields. The values provided within these fields are based on the "Releases" (aka "versions") within the project they are associated with.

Note: Archived releases will not show in either field.

https://www.atlassian.com/agile/tutorials/versions#:~:text=Affects%20version%20is%20the%20version,feature%20or%20bugfix%20to%20customers.

[lila]

As Gary mentioned, it is a system field not a custom one. You can find it under Field configuration > Default Field Configuration > Affects versions