Strange sssshhhhh sound from 10-25mph

Atlas goes in Tuesday for a strange for what I describe as Sssshhhhhhhh sound when I accelerate from 10-25 mph. Service tech said they definatlt hear it and can duplicate it. Going to check the transmission level. Sounds like they have to warm the car up to ma certain/exact temp to check the level. They will go from there. It has also in the first 1000 miles developed a strange shift from 1-2 gear that I will hopefully get an answer too. I just came from a 2015 that was a tranny nightmare with 2 TPS units replaced and the full tranny in the first 20K miles.