Windows Steam client only: new Steam Workshop UI dropdown arrows do not open/respond.

Examples:
- Browse ▼ does not open in the new Workshop UI.
- Legacy Workshop UI dropdowns work.
- Same Workshop page works fine in Chrome/Edge.
- Normal buttons work in Steam client.
- Rebooted Windows.
- Cleared Steam web browser data and deeper cache.
- Disabled GPU accelerated rendering in web views.
- Switched to Steam Beta; no change.
- DPI is standard.

Looks like a Steam client embedded webview / popover input bug specific to the new Workshop UI.