How long ago was the auto trans serviced? If it has been serviced then did they replace the filter in the trans?
Had a similar problem with my "other" car (different make), the dealer said there's no fault codes and there were no issues on a test drive plus they said the trans didn't need servicing (Yeah, right). Finally gave up on the dealer's advice & took it to a trans specialist to have it serviced. The fella said the trans oil was still okay in colour (mostly red & not brown) and replaced the trans filter. Most of the issues that plagued my "other" car's trans immediately disappeared after having the trans serviced. There were still a few niggling issues but they've slowly gone away as the new clean fluid has worked its way through the trans.
If it's been regularly serviced then hopefully the brains trust on this site has a few good pointers.