Incoming trackbacks broken in 1.5

Hi All,
I have a blog running at https://www.sacarny.com/blog/
I just upgraded to 1.5. I notice that now, unless the referent is running WordPress 1.5, an incoming trackback will not be recorded by my blog.
I set up another blog in my account using a separate installation of 1.5, and was able to trackback a post on my real blog. However, when I deleted this blog and made another one with version 1.2, then trackbacked the same article, the trackback did not appear. I saw no errors, so this is all failing silently.
Pingbacks work fine, BTW.
Is anyone else seeing this problem, and is there a fix out there or in the works?
Thanks,
Adam Sacarny