Yes the fact that both ISO 520 AND ISO 540 rims get called 24" and 24x1" at that is a PAIN but it doesn't stop there. ISO 507 and 547 are both called 24" as well. No the tire isn't compatible. Put it down to a learning experience. Actually the only ISO 520 tires I've seen were labeled 520 x 23c so there is no consistency that I can see.
Regards, Anthony