I am facing issue in getting the right Contact Key in Marketing cloud for mobile push
So here is the scenario - Recently we noticed that MC was populating with the correct SF contact key for some push contacts, but an GUID for the contact key value instead for some others. At that time, we investigated and found that our database had NULL for the contact key for the problematic contacts. To fix that, we added the correct values into our database and deleted the unwanted contacts from MC. However, we're seeing that since then, more contacts are being created in MC with the GUID as contact key.
What could be the possible reasons? I am aware of setDelayRegistrationUntilContactKeyIsSet() for Android as True in order to get the contacts created with the right contact key present in the database. But if this was not set earlier then how some of the contacts were mapped with correct contact key & not GUID .