Titans' Nest mana not useable with Mnemonic Betrayal

I was unable to cast a Kaya's Wrath with the colorless mana produced off Titans' Nest. The way Mnemonic Betrayal is worded should let you cast the exiled spells using "mana of any color" and the spells in exile meet the restriction on Titans' Nest mana colored spells with no X in cost.

Edit: On second test I realized it does pay for the colorless but not the colored mana.

**Situation:
Kaya's Wrath in the Exile Zone via Mnemonic Betrayal.
Titans' Nest activated ability used producing 1 colorless mana.
Kaya's Wrath can't use the colorless mana even though it meets all the requirements.**