I'm afraid I don't know much about those but I wonder if they have any built-in adjustability, or known hacks? Like some have a movable tube, others can be adjusted with cork or silicon discs, etc. Have you seen discussion of this cap phenomenon or these types of adjustments in the KB threads?
Maybe your KB is tuned for older, ferrous caps and doesn't interact as well with the newer formulation, but it's interesting that it's that stark. My IHs all work differently but most differ more by tip than by cap.
If you go have a look at the Fluxer thread, iirc, there was a good bit of examination around this issue, that there were some older caps with metal content that was very interactive with induction. As I recall, DV altered that with the rising IH popularity because it made them too susceptible to combusting. In any case the members identified different caps and their metal content, their reactivity, etc. It's mostly over my head but really interesting. I'm almost sure key info resides there.
Indeed. Do you ever torch them? How different do they seem torched?