SOLVED: Get(AccountName) returns an unexpected (to me) value; external authentication (Active Directory); in WebDirect

[ken_s2007]

UPDATE: A user claimed to have been clicking a checkbox, which has a script trigger to run a script. The script wasn't executing at times. I misdiagnosed the problem. Sorry for the trouble (I see no way to delete my post here).

ORIGINAL POST:

I have a database using external authentication (via Active Directory). FileMaker Server 17.

Scripting using Get(AccountName) (using some logic ("if") based on an expectation of a particular AD account name, and other functionality) works fine in FileMaker Pro 16 Advanced (returning a value like "smith"; the user's AD account name), but lately, the script isn't executing as expected *at times*, when using WebDirect. I created a script to display the user's AccountName, and instead returning "smith", the WebDirect user's AccountName is in the form of:

[WebDirect-DC288] [UPDATE: That was actually being returned by Get(UserName), not Get(AccountName).]

... which seems to be causing the problem.

An explanation of why that is being returned would be much appreciated.

Edited April 15, 2019 by ken_s2007
I discovered my incorrect diagnosis