Could Not Reproduce Bug Six with Damping Matrix

[Akkarin]

I can't cast cards from graveyard from Six ability (retrace), because Damping Matrix in play. This is bug besacuse ruling: (https://gatherer.wizards.com/pages/card/Details.aspx?multiverseid=426043)
Damping Matrix's ability affects only artifacts and creatures on the battlefield. Activated abilities that work in other zones (such as bloodrush or unearth) can still be activated. Triggered abilities (starting with "when," "whenever," or "at") are unaffected.

 

[Neo001992]

In testing this functions as expected, and I was able to cast nonland permanents from the graveyard. This would lead me to ask if there was something else in play that might have been effecting your ability to cast spells form the graveyard?

https://imgur.com/a/Y68cbjX

Event#269966730 Game#883048998

 

[Akkarin]

I don't think there was anything else that would have influenced it. I clicked in Sowing Mycospawn in my graveyard and nothing happened.

 

[Neo001992]

I don't think there was anything else that would have influenced it. I clicked in Sowing Mycospawn in my graveyard and nothing happened.

To ask the obvious question, did you have the land in hand to discard to pay the retrace cost?