Cannot create new pages

Since updating to this new version, I cannot create a page anywhere in the page tree. I’ve tried both ways:

1. Selecting the parent page, clicking Add Page in the right panel.
2. Adding the page title in the field at the bottom and dragging it to the correct position.

With both scenario, it looks as if it’s creating the page, but it never appears in the page tree, and searching for it give zero results, so it’s not just hidden elsewhere. It simply won’t get created.