I've been using two of these for a few years now with no problems in a Nikon D300.
Yeah– I’ve totally had the red CF Type 1 adapter not even recognize in 4th gens, but weirdly enough it’s proven to be mostly reliable in this Mini.
The iFlash CF adapters totally do work, but I’ve also found that this Type II CF card adapter from Amazon is every bit as reliable: https://www.amazon.com/dp/B00EPMWT1M/ref=cm_sw_r_cp_api_fabt1_2xwSFbV2418FT?_encoding=UTF8&psc=1
They work reliably in other iPods for anyone looking for a cheaper, faster shipping CF card option– haven’t tried one in a Mini, and they are slightly thicker but not much more so than the original Microdrive so it should fit fine.