Having this issue on multiple boards and multiple connect-board ‘board-relation’ columns. Not sure when it became a problem.
Per https://api.developer.monday.com/docs/connect#reading-the-connect-boards-column - the API should return the data.
Hello @bmack!
We are going to need you to please send this information to appsupport@monday.com so we can take a closer look into it, look into the logs and give this issue some following 
Have either of you gotten a resolution on this? I have recently experienced the same issue.
I submitted a ticket in with Monday.com support shortly after posting. Have some dialog back and forth but no fix at this time.
Thanks for the update. Please let us know if you find out anything.
fyi…