Welcome @Jason_Orchard !
If you are using the sync that is available from the project action menu (like in the image) I would advise against it. I have found it unreliable.
Syncing this with outlook web over Outlook desktop still makes it unreliable.
A more reliable (and near instant sync) would be to use the 📅 New and Improved Asana to Outlook Calendar Sync!
It still is one way sync sadly.