Post Indexer site-specific settings won't stick

When I go to the site-specific settings of the Post Indexer to select per-site custom post types for indexing, I use the checkboxes to add a few options, and then click on “Save All Settings” and….nothing happens. If I click “rebuild” it’s still doing just the globals, and if I go back to the “edit” screen, only the globals are selected — the custom ones I just chose are no longer checked.

I enabled support access. Hope we can sort this out. Thanks!