At first glance, this would appear to be a contradiction. However, upon investigation, I found this article that I think explains in much detail what you are seeing.
Spoiler alert, I think the read-ahead feature is saving this particular counter and may actually be misleading. Reading Pages
Thanks for that - very detailed.
I'll add BCHR to the list of things that are not really useful (along with PLE in isolation..................) so to be ignored for the most part.
I had wondered if this (or the fact we have SSDs, or disk cache etc) was obfuscating what was really happening, but had discounted this assuming that that MS would account for whether Read Ahead was Active or not, and it's impact on the Metrics provided.