Unable to access network smb shares using Serv-U

I have a few Serv-U setups running, and some of them are using external smb shares like NAS or windows file shares requiring authentication.
My Serv-U servers are not domain joined and my serv-u services are running as a local service account on the server. My storage solutions are often domain joined or at least using ldap for authentication users requiring me to use a domain account to access the share.
If i'm on the server trying to access the share i get prompt for user/pw. After user/pw input i can access the share.
Using the same logic I'm able to add the share as a persistent disk or even add my credentials using cmdkey as the same user running serv-u service. This allows me to access the share in windows, however wont have any effect in Serv-U it seems.

Going into Serv-U Management - Adding the share as a directory, entering user/pw/domain should have given me the same behaviour. However it seems this have no effect. 
Adding the share as homedirectory on one of my users, or as a addon directory using virtual directory gives me an error that the directory does not exist or no error just not showing up in the list as all.
The same goes for domain directory rules adding the share with user/pw/domain with no effect

I'm guessing had I had my server and NAS joined to the same domain and had my services run as the same user having access to the share this would work. However this is not an option.

Using the method above seem to have worked on previous versions of Serv-U Version 15.2 (15.2.3.742) and older. I'm currently on 15.4 and had the same issue on 15.3.

Errors:

[02] Thu 01Jun23 15:33:22 - (000073) Error logging in user "USERNAME", home dir "\\domain.local\data\SFTP\" does not exist