UPDATE: I discovered the solution below was only working when the Title base field was enabled for the entity type. If you enable the title field on the entity type it works, but then the title is required to save a new record. I will look for an alternative solution to avoid using the Title field altogether. Also, I’ll look into https://www.drupal.org/project/eck/issues/2785297.
I’ve recently run into an issue with an ECK-created custom entity type. There was no reason for me to use the “Title” field on this particular entity type. Unfortunately, when you don’t have a title field several of the built-in entity listings and displays seem broken. Here’s what the Content List screen looks like, for example: