l always have had great success with pavlovas. Recently l bought a new double oven. l made a pavlova and put it in the small oven. A complete disaster. l made another and put it in the bigger oven - same thing. The meringue was coming away from the sides and it was flat and soft. Have tried another three times with the same result. Is it the oven ? ? ?
Your new oven might be off in temperature calibration.
Or your old oven might have been off in temperature calibration, but you were used to it - so you set the new oven where you set the old oven, and even if the new oven temperature is correct as set, it's not what the old one was when set there.
If there are other differences between the ovens (fuel source, convection fan or lack thereof, etc.) those may also play a role.