Whenever I modify a note on windows, android gives me the "Some items cannot be decrypted" notification. Whenever I create or modify a note on android, windows decrypts it no problem.
I had the exact same issue, which brought me here. Updating the Android app to the latest version available on Google Play solved this for me. (I had somehow disabled updates for it.) I see you are using an older version of the Android app so you may want to consider updating it.
Ya know, the funny thing is, I thought about that but the store initially said there were no updates required, but when I went to the app page it gave me the option to update. I love computers.