’12 Nissan Rogue CVT whine and RPM jumps

2012 Nissan Rogue 2.5 S. 40,555 miles. When starting out from a stop the RPM’s rev as they should to get the vehicle up to speed, but out of nowhere the RPM’s drop suddenly about 1,000 RPM’s. Then jerks back up to a higher RPM again because I am still accelerating up to speed. This happens more so when climbing a hill from a stop, but also when in a straight away. The issue is more jerky and pronounce when then engine is still not warmed up to Operating Temp.

There is also a very noisy whine coming from the CVT once engine is warmed up and I have been doing a lot of driving especially on a hill and hot day. I own two Altima’s with CVT’s and neither have these issues.

I’ve been to two dealers and both say nothing wrong just because there are no codes. Factory power train warranty runs out in October. Fluid looks clean and at correct level. I ask the dealer about a software update, but they ignore me and look at me like I don’t know what I’m talking about.

Any suggesting?