I'm sorry to use this forum incorrectly. I'm not here to contribute idea, but rather seeking help. The zendesk on your website doesn't help to solve the issue.
I have the GoodNotes 5 on my IpadPro and recently I downloaded the same apps on my iphone 11. During the syncing, there is a pop-up message to urge me to update the GoodNotes 5 on my IpadPro or it is unable to sync. Both apps were updated and I restarted both devices. But the problem persist. I need some help but do not know where to get it... Hope to hear from you.