Design corrupted in Preview/Upload when opening a Sitely 6 site in Sitely 7

Sitely version: 7 (build 41039), Mac App Store release
macOS: 26.6.2

Description:
I opened a website originally created in Sitely 6 using Sitely 7. The site displays correctly in Design mode, but the layout breaks/corrupts when:

  • Switching to Preview mode

  • Uploading the site to the server

    Would it be possible to get access to the Sitely 7 beta version, to check whether it resolves this migration issue?

Short video:

ScreenFlow

Detailed view: