Existing entities not being shown

I am trying to show an entity reference (from ECK) in an entity form and if I choose inline multiple values, I only see a title and the "add new group" and "add existing group" buttons, but no way to choose an entity. The buttons work, but I have to guess whether I need an existing or new entity without being able to see a list of entities.

Any thoughts about why this might be? The entity contains another entity reference as a field, but my understanding is that more than one level is supposed to be supported.

Thanks for any help.

Also, as a side note, I think that I used to be able to paste images as part of an issue summary, but I don't see how to do that now.