Diagnosis
No. A constant hiss during pressure cooking means the steam release valve is not fully sealed. The silicone sealing ring or the valve stem is the issue.
How to Fix It
Turn the pot off and release pressure. Check the steam release handle is fully turned to "Sealing." Remove the silicone cap from the float valve. Remove the anti-block shield. Re-seat the clear silicone sealing ring, ensuring it's not pinched or folded.
If That Didn't Work
The steam release valve itself may have food debris. Remove it by pulling it straight up from the lid. Wash the valve and its housing. Reinsert firmly.
Heads Up
A constant hiss means pressure is escaping. Cooking times will be inaccurate and the pot may not reach full pressure. Fix it before continuing.