I don't currently have an outbreak and I do dose aminos twice a week in 2 of our tanks.
anecdotal evidence for both myself and at least a couple others seem to indicate that low Mg levels may help Cyano go on a growth craze.
So much so that a R2R user had a blanket of cyano in his tank. Mg levels were below 1200 - within an hour of Mg levels being increased the cyano start lifting off the surfaces with no other (apparent) changes.
I've also seen a build up of cyano in conjuction with whitening of coralline algae - again - during a period of low Mg.
I'm just looking to hear anyone else that may be currently, or have previously, experienced something similar.