That's currently the expected behavior for ADDUSER cmd on newer products (4-Series, TSx-x70, NVX, etc). After ADDUSER cmd is issued on these devices, you must then log in with the temporary password, and respond to the prompt to create a permanent password. Feature Requests were submitted to these product teams to add an option / flag to the ADDUSER command to make the newly created user's credentials permanent.
Personally I used several Toolbox Scripts that I wrote on the fly during a support call where we were changing previous creds (I think they still had admin:admin) to meet the new 7chr password requirements for newest NVX / DIR FW versions. The first sent the new ADDUSER cmd to all the endpoints. The second logged into all endpoints using the newly created account w/ temporary credentials - at which point many Toolbox popups appeared to Enter+Confirm New Password. I just repeatedly used CTRL+V, TAB, ENTER to assert them. Powershell EDK may be able to assert the new permanent PW (I'm not sure offhand), but to my knowledge Toolbox & Toolbox Scripting will always produce popup prompts to do this (no way to suppress the popups and configure everything from within the script).
Dave H - Crestron True Blue Tech Support Engineer Since 2014