The upgrade from SMF 1.1.11 to 2.07 has resulted in some personal messaging profile settings being reset to default values.
One value worthy of particular note is the "Receive personal messages from:" setting, which appears to have defaulted during the upgrade to "Administrators Only".
If you send or receive personal messages using the forum facilities, please do re-check your Profile > Account Settings > Personal Messaging settings to make sure they're as you prefer them.
My apologies for any inconvenience.