unexpected behavior and debugging help

[breadwild]

We were using this plugin to connect bbpress forums with a custom post type called discussions. The forum list was appearing as a dropdown (select) on the edit screen for each discussion unit. The dropdown listed all the created forums, so we could select a forum that would be associated with that discussion.

Here's the issue. We noticed that the select dropdown disappeared several weeks ago. We are not sure if this happened after a wordpress upgrade or not. We've disabled other plugins to see if there is a conflict, but that has not solved the problem. Also, no errors are appearing on the screen, in the inspector, or in our apache logs. How can we debug this?

Should we be seeing "forum" as a field type in when we edit an ACF field group? What settings should we use to activate the dropdown?

Thanks!