The Synotes update released on 17th of November has a known bug. This has been rectified and submitted to Apple and is currently waiting for them to release it.
Unfortunately there are some notes that cannot be accessed through the application, these notes have not been lost. If you need to gain access to your notes please login to the web app using your browser. https://synotes.syncode.co.uk/
We are sorry for any inconvenience caused.
Syncode support team.