It did let him enter an OS login of "RND/abc". But when he then logged into his OS as RND/abc, then into Appx, it told him - "Bad User Id - The User Id you are currently using was not found in the APPX user file."

VAR deleted .\data\0SA\Data\USER.* in order to be able to enter Appx. In Security > Users he tried entering "abc", but it gave him the "not currently defined" message. It did let him enter an OS Login ID of "RND/abc", but again wouldn't let "abc" log in.

VAR didn't notice that there was the word "Warning" in front of the first message. Because of confusion of local IDs and domain ID, Appx validates against the domain id, but allows entry of only the user portion of the Domain/User ID.

I.E., "abc" works for logging in, but generates a Warning during OS Login ID Entry. "RND/abc" doesn't work for logging in, but generates no warning during OS Login ID entry.

If you're in a Domain environment, enter only the user part of the user's OS Login ID. Also, ignore the "Warning - This ID is not currently defined..." message.

Note, this message was changed from 'Error' to 'Warning' in 4.1.8. If your Appx version is prior to 4.1.8, it's probably necessary to upgrade to 4.1.8 or higher in order to be able to enter OS Login ID’s.