ICAT metadata objects no longer autocomplete

We no longer have autocomplete for some metadata objects:

DEMO_SESSION [1]: SCAN_SAVING.collection.definitions...  # autocomplete works
DEMO_SESSION [2]: SCAN_SAVING.proposal.definitions...  # autocomplete works

DEMO_SESSION [3]: SCAN_SAVING.dataset.definitions....  # autocomplete does NOT work
DEMO_SESSION [4]: SCAN_SAVING.sample.definitions....  # autocomplete does NOT work