Delay in grant for SN 190 Victoria for Agriculture Scientist


I applied for Visa subclass 190 under the occupation 234112 Agriculture Scientist. My Lodgement Date was 23rd Aug 2019. I have recived mail for additional document on Jan 29th, 2019 which I provided immediately on Feb 2nd, 2020.Till now I have not received my Grant. It has been 19 months now. Is there anyone who can explain to me this delay what might be the reasons for this.