`ui` not starting on windows release as configured

Describe and demonstrate the bug

I'm not sure what's going on here. The environment has UCM_WEB_UI correctly set, but ucm doesn't pick it up.

The video shows I can pass UCM_WEB_UI on the command-line with --ui, I think somehow the environment isn't being inherited by unison.exe?

using call <exe> in the batch file doesn't seem to help.

Screenshots

Environment (please complete the following information):

Additional context n/a

unisonweb / unison