Hard shifting in second gear when car is cold.

I have a 2016 2.0L automatic Mazda 3 and have had an ongoing issue with hard shifting from first gear into second. It only happens from first to second and goes away after driving for a bit. Fluid has been checked and is fine, spark plugs are new. No check engine light and no TCM codes. I’ve taken it to multiple shops and they couldn’t figure out what’s wrong without tearing apart my car. It almost feels like it drops rpm twice when shifting. Figured this would be the best place to try and solve this. Thanks in advance.