Arelith

Invoker's can't take any epic spells unless they have 22 CHA hard ranks, no matter of spellcraft they have.

Was tested with hard CHA 19 - 21 with no success, only with 22 CHA are able to pick any Epic Spell. Other spontaneous casters as Sorc need only 19 CHA.

This renders builds which are not interested in deep investment in Charisma unable to make.
I expect this not to be intended.

Not a bug.
Invokers requiere a base score of 22 points to use epic spells.
This is intended behaviour to balance the unique feature of infinite spells.

A note has been added to the wiki.
Locked and moved.