I nailed it again, I think
The problematic slaves are detected correctly if you are using a 2-level structure, and fails if you are using single-level structures. I guess your routine is different between the two?
Anyway, this information should be what you need to understand why some of us have problems.
Can the people who have reported missing slaves confirm that they are running 1-level structures?
Just to explain what this actually means, here is an example:
1-level structure: demos:9Fingers
2-level structure: demos:0_9/9Fingers