I don't see a problem. It isn't the ring failing to create something , after all a power ring can 'do anything' with sufficient willpower (I remember seeing a few scans wherein a Lantern attempts to reverse time by an hour to re-charge his ring, the results are, ah- , odd too say the least....). It's just that John is pumping out willpower faster then the Ring can convert.
His will is overloading the ring to the point that it's giving him a warning message. That's ridiculous and hardly consistent with the ring's feats and powers.
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Graffiti outside Latin class.
Sed quis custodiet ipsos custodes?
A juvenal prank.