So, it depends on what you mean by “mapped”. If you mean what Windows means, then my experience is exactly the opposite of yours. If you mean "a network drive accessed directly by UNC, not by a Windows OS Z:-style alias, which WIndows calls a ‘map’ ", then I can confirm your results:

My experiment:

1. I have a directory on a remote machine available from \\machinename\path\
2. I use Windows “map” feature (right click on This PC, then click Map Network Drive, and map \\machinename\path\ to the drive Z:\ – this is a Windows map.
3. In Notepad++, I use File > Open Folder As Workspace twice.
   1. The first time, I select Z:\, and I see it show me the whole hierarchy
   2. The second time, I select \\machinename\path\, and I see it show me the whole hierarchy
4. In Windows, I add a new file to \\machinename\path\
5. Instantly, the Z: portion in Notepad++'s Folder as Workspace panel shows me the new file. However, the \\machinename\path\ portion in Notepad++'s Folder as Workspace panel does not update

(I see the same behavior on both v8.2.1 and v8.3.2)

If possible, I would recommend just using Windows to map the UNC path to a pseudo-drive-letter, like I did for Z:. If you don’t want to do that long term, then you can read the “feature request” FAQ which explains how and where to make an official feature request. If you do make a feature request, make sure you follow their template (especially include the Debug Info of your current Notepad++, by going to the ? menu and clicking Debug Info); also, make sure you use correct terminology: a mapped drive is a drive letter that points somewhere else (like my example Z: points to the remote machine); a UNC path is using the double-backslashed \\machinename\path\ to access the machine directly, without a Windows mapping. Finally, if you create that request, please paste a link to that request in reply to this topic, so future people who find your request here can find out if it’s been implemented yet or not.

Good luck.