I second the replace tranny oil.
Actually, there are many dealerships that I would NOT trust to put in the correct fluid, in the correct amount.
Just talking out of my anal pore, I would think a Polaris dealer that was totally devoted to ICE bikes, could well be among those service departments not up to speed on Empulses, especially given that those bikes probably didn't get management all hot and excited by their huge sales performance.
When you drain the transmission, it would be a good idea to measure what comes out; should be about 1L.
Have you checked the alignment of the chain on the sprockets? I find this tool much more precise than marks on the swingarm:
https://www.amazon.com/Motion-Pro-08-0048-Chain-Alignment/dp/B000GTVOJQ One other possibility leaks into what passes for my brain: It could be the first signs of a rear wheel bearing failure. Several of us have had those fail (search threads) and, since the OEM bearings don't have a weather seal and since you appear to be where it rains alot....