Sadly we have something very similar :-(
Our 2017 Niro is only 4 months old.
It has already been in to Kia Service for sluggish performance and hesitant or stuck or missed gear changes/revs, and the Orange Engine Light on.
This was at about 1400 miles.
It went into the Service Dept at Kia. for 5 full days ... they said they could not find anything wrong, so they updated the latest software firmware.
Seemed OK after that.
We are now away on holiday and it's started again today at 1800 miles, only worse.
We stopped for 30 minutes, but that made no difference.
We went to a local Kia dealership [it's Sunday, service is closed] and their Sales chaps gave it a quick drive and when they came back it was OK as regards the semi-hesitant weird gear/rev changes.
I would say this is happening around 2nd to 3rd gear with the petrol engine, maybe also 5th gear too...
The Orange light was still on, which they said was only an advisory alert.
I also suspect it is using the electric less and less also ... something is awry here :-(
Having had this issue twice now, and reading this Forum, I do not think this vehicle model is perfected yet.
We will call our local Kia. Service in the morning, the ones who had it last and could find nothing... but I can only see this situation escalating as this issue is not right at all.