Cannot delete some pages with xclass and an xobject from that xclass

Reproduction steps:

• Import the attached XAR as admin or create a page with an XClass and an XObject of that XClass (for example with a single timezone property)
• Set your user as advanced user to get the question about breaking xclass
• Go to the imported page and click on delete
• When asking about the breaking xclass, select the page and confirm

Expected result:

• The page is properly deleted

Obtained result:

• The result of the deletion shows a success message with "Done" but the page is still there