Priority Not Given
As described above, I wanted to save my 4/4 Token Angel sacrificing my Selfless Savior, but the system did not allowed my as the system resolved the damage directly after the Titanic Growth was casted, then I had no option to save my Angel Token as I should have been allowed. Consequently I lost the match because of it.
As it was detrimental to me, an caused by a malfunctioning of the MTGO client, I would appreciate the reimbursement of the event fee.
Same issue on at least 3 different occasions all with Selfless Saviour