Ive heard about a glitch with the artronarch stone. the glitch is 50% of the time your summons fail as it counts as cast on yourself, meaning it is absorbed it this true?

Yes, you can absorb your own spells. At least conjuration.

You conjurations can indeed fail when you have the stone, Usually not that much of a problem as you will regain more mana than you spent But it is quite annoying for the greater power summon(s)

Yes, this is true. I found this out the hard way. Having to cast your summons 3 to 5 times before they finally get summoned gets annoying quite fast.