SmartScreen (or other) blocking legitimate software?

We have Symantec Wise Package Studio to build simple custom MSI files (Yes I know the product is beyond end-of-life but for our needs it serves it's purpose)

It used to work fine but now when we try to run it , the main executable "PackageStudio8.exe" gets blocked by something which seems to be SmartScreen maybe?

Translation : This application has been blocked for your protection.
An administrator prevents you from running this application. To know more, contact the administrator.

Could it be some kind of GPO I don't know about?

Based on web findings I tried setting the following values :

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer]
"SmartScreenEnabled"="Off"

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\System]
"EnableSmartScreen"=dword:00000000
"ShellSmartScreenLevel"=-

But it doesn't change anything, it still gets blocked and that window still appears. Turning off SmartScreen (disabled) in the Windows 10 GUI still doesn't make it go away.

Interesting thing I noticed is if you open a shell (cmd or powershell) AS AN ADMINISTRATOR and run the exe, it runs fine and everything works. So for now we make do by running it as administator, but it's not ideal.

What gets bypassed when you run as admin and how can I find and adjust what creates this prompt?

Much appreciated.

Turns out it's UAC actually. I found out that the only way to get rid of that prompt is to completly disable UAC for example : HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System (set value ' EnableLUA' to 0) but of course it's a security risk. I guess the safer way is to run it as administrator simply, instead of getting rid of UAC completly just for that program! Wondering why UAC blocks it though? Is it because the app has "EDITOR/PUBLISHER : UNKNOWN" ?