Jeff,
This cut was a follow-up of this first try that went perfectly fine with:
102Z 1/8" ZrN coated endmill / adaptive clearing toolpath, 10.000 RPM, 762mm/min feed, 0.305mm optimal load, DOC around 0.3"
I then tried increasing the optimal load to 0.4mm, the cut started just fine, but I had mistakenly set my air jet to a lower flow than on the first try, and after a while, I got an accumulation of chips in a deep/corner area, and that’s when I had this melting issue.
I have rerun this job just now, with more air and a little spray of WD40 now and then, and it went perfectly.