[ID-4260022][ExtendScript] Folder.prototype.create fails on macOS/InDesign 20.1
Something has broken in ExtendScript's Folder.prototype.create method on MacOS and Indesign 20.1.
To test yourself, save the following script to your disk, and run it in Indesign.
(function () {
var scriptFolder = File($.fileName).parent;
var deepFolder = Folder(scriptFolder + '/A/B/C/D');
if (!deepFolder.exists)
deepFolder.create();
if (deepFolder.exists) {
alert('Folder created successfully.');
}
else {
alert('Failed to create folder "' + deepFolder.fsName + '".');
}
})();
Expected Result:
Prior to this bug, this script would successfully create the folder and subfolders, in the same folder as the script is saved.
Actual Result:
Each time the script is run, it creates only one more level of sub folder. So the first time run it creates folder "A", then the next time run it creates "B" etc.
See also this thread on the forum.

Hi,
Thank you for reporting the issue. We have been able to reproduce the issue and it is currently under investigation.
—
Adobe InDesign Team