SPFx Form Customizer - isPanelExperienceEnabled - Not Working

Target SharePoint environment

SharePoint Online

What SharePoint development model, framework, SDK or API is this about?

💥 SharePoint Framework

Developer environment

Windows

What browser(s) / client(s) have you tested

• 💥 Internet Explorer
• 💥 Microsoft Edge
• 💥 Google Chrome
• 💥 FireFox
• 💥 Safari
• mobile (iOS/iPadOS)
• mobile (Android)
• not applicable
• other (enter in the "Additional environment details" area below)

Additional environment details

• SPFx version: 1.24.0-beta.2
• Microsoft 365 Targeted Release

Describe the bug / error

I've enabled the newer, but apparently fully GA, property isPanelExperienceEnabled in my form customizer manifest.
I've deployed this solution, more than 24h ago, but the forms still show up in the old seperate aspx pages not in the panel. New opens a new page and renders my custom form. Edit opens in a new page and renders my custom form. Sadly, the details pane, which would open a new page with the "view" for my custom form, now does nothing but show the view panel with no column properties.

New/Edit Render:

Details:

Steps to reproduce

1. Create an SPFx solution with a form customizer.
2. Add the new isPanelExperienceEnabled: true property
3. Deploy the solution.
4. Use the list the form customizer is attached to.

Expected behavior

This should now open in the new panel experience.