Did Self-Pingbacks Stop Working?

I have noticed that for the last couple of releases, pingbacks to posts within the same blog have stopped working. The blog still pingbacks other blogs, however.

I did read the documentation and have checked that the full URL is present in the blog post for each link I am trying to execute a pingback with. I have also checked the settings and pingbacks are enabled, both for the posts themselves and for the entire blog.

Also, the pingbacks do not appear at all under comments, not even as pending.

It should be noted that this blog does not have permalinks enabled. (Never could get it working on this particular server, for some reason.)

The only way I can add a pseudo permalink is to create a normal comment, and then go into the database and change the type to pingback and set the user to 0. This is a bit of a pain just to add a permalink.

Any idea why it stopped working? Do self-pingbacks no longer work in the new versions?

Example: https://blog.morepossibilities.info/?p=2842 should have pinged https://blog.morepossibilities.info/?p=2832 and another post but did not.