Incompatible with plone.app.iterate: all comments are gone after check-in

[zjs2k]

I am running Plone 4.3.7, with plone.app.discussion 2.2.15, and plone.app.iterate 2.1.13 pinned by Plone. If a content (my own custom Dexterity content type) has iterate (staging) enabled and it has comments, I got an error when I try to check-in the working copy, or try to cancel the checkout:
ERROR Zope.ZCatalog uncatalogObject unsuccessfully attempted to uncatalog an object with a uid of /Plone/stories/story-1/copy_of_chapter-one/++conversation++default/1459989773220166.

If I was just canceling the checkout, nothing bad happens apparently. But if I check-in the working copy, the updated original content will lose all the comments. The comments are still listed in portal_catalog, but no longer on the content page.

It looks like when check-in tries to delete the working copy, it tries to unindex the comment and gives above error. Any suggestion how to fix this? Thanks!