Not seeing any notes on the card

[abdo.nh]

Regarding the error:

Sync Error

The last add-on release introduced an unintentional incompatibility with with older Anki versions. We’ll look into a fix but I recommend updating your Anki if nothing prevents you from using newer versions.

Regarding empty notes, try using the AnkiHub > Reset all local changes to a deck menu item in the browser.