Just a thought... probably a red herring, but worth asking...

Collections items are just references to the actual content in your Runtime libraries.
You haven't moved (or renamed, or re-organised) your Runtime(s) since creating the Collection items, have you? If so, you may have broken the references.

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)