Incase anyone reads this, the answer was I had too many dependency properties.
I could still see an object's properties in the command window - just not in the variable editor where it's the most useful.
As for the maximum number of dependency properties before this happens.... I don't know. It actually seemed to vary.
I removed a lot and now my class/objects can be viewed fine.
I was only using dependency properties as I wanted to get and sort the values quickly. arrayfun requires slightly more thinking but can perform the same job.
All the best,
Tom.
