To be honest, we found out by mistake. She forgot to put the plug in, and the lights went down to around half way. Page 3 of the manual says:
Sometimes manufacturers change where the power induction pickup is in the case and it won’t charge aids that are not designed for it.
I had exactly this problem with GN Resound One aids that wouldn’t charge from the premium case that was supplied with my earlier Resound Linx Quattro aids. The correct case looks exactly the same, but the Ones sit just a bit lower than in the earlier case. It was an annoying problem that no one believed at the time.