Evans waterless coolant

The problem with Evans coolant is it’s basically straight antifreeze and it doesn’t have the heat transfer properties of water. There’s a thread from a few years back on here that discussed Evans coolant and yes I switched back to 50/50 due to some of the same issues you were having.
Here’s a write up about it (not saying it’s gospel since it’s written by another company) but I tend to agree.
No-Rosion Products Technical Questions and Answers