If the issue is with the file then you should be able to get the problem to show up on other media. Have you tried that?
The most likely reason is the combination of parameters in place when you run the job. The media, the file, the profile, the ink saturation, the resolution, the heat settings, the temperature and humidity in your shop, etc. What you must do to track it down is to experiment with modifying each parameter in your combination to see what may affect it. In such troubleshooting, it is best to not only determine what is wrong, but also to determine what is right or as it should be.
Without any pictures from you, it's hard to speak in anything other than generalities. So I suggest you post some. An educated guess as to where your problem most likely rests is that you are seeing a reaction in the film to the solvents in the ink after heat has been applied to the film. What happens if you crop out a small section of your film and run it at a lower heat setting? A higher heat setting? A lower ink saturation? A different resolution?
Sometimes you get situations that simply defy all logic and all you can do is avoid them in the future. For example:
On my Gerber Edge, when I try to print spot or process black foil on Oracal 751 Gold vinyl, using brand X it fails and brand Y it works. Yet any other film works fine with Brand X Spot Black or Process Black and any other Brand X color will print just fine on Oracal 751 Gold. No changes in my settings have any effect. There is no logical reason to explain the problem so avoiding the combination of Brand X Black and Oracal 751 Gold is our only solution.
