2017 Kia Sportage - RPMs rise oddly

Driving the car it seems to go into neutral, RPM will increases.
then decreases then goes back to normal. Doesn’t happen at any specific speed and not all the time. Took it to the dealer had a diagnostic test done. they drove it for 11 miles and checked for codes. No codes and didn’t do it when they drove. Anyone have these issues. of course this year of sportage gave us oil consumption issues. and kia evidentally doesn’t see it as a recall issue

That is the classic description of a transmission that is beginning to slip. Rather than relying solely on the dealership, I suggest that you have an independent transmission shop give you their opinion/diagnosis.

Assuming that your 10 year Powertrain Warranty is in effect, you might be able to convince the dealership that your transmission is starting to fail if you give them a printed diagnosis from a local, respected transmission shop. (Note: That means a shop OTHER than Mr. Transmission, Cottman, Lee Myles or AAMCO.)