I built two custom post types and I connected together.
Everything seems to be working fine, I can see the connection in connection types , but there are no metaboxes to make it visually.
Separated tests connecting posts and pages work just fine, so I guess I have something missing/wrong on the custom post types.
I thought it was something related with register_meta_box_cb but I didn't figure it out yet.
Any clues appreciated.