Yup, that was it.
I also commented out the $activity['available'] reference in
https://github.com/deraadt/moodle-block_completion_progress/blob/master/lib.php#L549
to get the description to be linked as well.
I think you probably want to look at
https://github.com/deraadt/moodle-block_completion_progress/blob/master/lib.php#L426
to see why has_capability is setting that array element to false.
I set the activity to hidden, and the block just removed that element anyway which is fine.