This is incorrect. The magnetic flux will induce an electromotive force that will cause a current to flow in any conducting material and cause heating if this material is not superconducting.
As an example, induction heating is a commonly used method in zone melting for Si-purification [0].
The effect is more pronounced in ferromagnetic materials because a larger flux is induced.
A myth. Copper and aluminium won't heat on a consumer-grade kitchen induction stove, which only have a set of coils designed for ferrous metals, but restaurant kitchen professional IH stoves can use the different frequencies that heat non-ferrous metals, and a forge or melting furnace can indeed melt any metal, ferrous or not.
Why don't residential induction stoves have that capacity? Given the popularity of aluminum and copper cookware I'd think it would be pushed out. It's one thing people always bring up with induction ranges.
You can even do induction hardening. Used for complex parts, of if you want hardening with a very well defined penetration depth.
The place I used to go had a gas furnace to heat the metal. A pitty I didn't find time to go there for ages now... Only downside of gas furnace, closed on on end, is the limited length of the stuff you can put in. I have an idea I want to try to forge longer things, but again, it is months now I didn't have time to get back to it...
Yeah, but it is not mine! Also, there is a open gas forge sitting right next to it. So, the place decided if some work and investment is done, it will be on the open forge. Which I can only support!
But yeah, I just realized the last time I was there was last year before christmas... Good thing anout this is: the day I retire I will definitely not be bored at all!
https://youtu.be/P_STrnP__D4