My first guess is that you are not using Gerber vinyl and/or Gerber foils. Black foil is particularly troublesome as is Oracal vinyl.
To be clear ... I Edge print primarily with Apex foils (rebranded Duracoat) and used to use a lot of Oracal films. A good while back i started having transfer problems where black foil and Oracal films were combined. In every instance, the foil would print just fine on other films and other foils would print just fine on the film giving the problem.
The solution, for me, was to keep some Gerber Spot Black foil on hand for problem prints and to phase out the Oracal in favor of Gerber/3M vinyl. In particular, black third party foils seem to have the greatest problem with not printing well on certain vinyls.