In presence VCard photo hash is sent in hex representation of hash value. While Tigase Mobile Messenger calculates hash and stores it's value in lowercase hex representation, some clients send in presence uppercase hex representation of hash value of photo from VCard.

In this case VCard for clients sending photo hash in uppercase hex is retrieved every time presence is received by client.

Easiest way to fix would be to convert hex representation from uppercase to lowercase in checkVCardHash method of RosterProviderExt before it is passed for SQL query as a parameter.