Ombre generation causing color streaks in final print

We are a custom performance apparel manufacturing that does custom sublimated graphics in house, and we've noticed a consistent issue with some of our ombres. When the pieces are exported from Corel into PDFs, and when they are then printed on our sublimation printers, there are faint streaks of either red or blue that show up within the transition of the ombre.

Speaking with our printer technician, he informed us that it was not an issue with out printers, but rather with the way Corel generates the ombres. We've attempted exporting the pieces as different file types, changing some of the ombre settings in the Properties tag, trying different CMYK color values, and nothing has yielded any significant results. Turning the images into bitmaps before exporting is off the table, as it changes the CMYK values of our colors and often lowers the resolution too much to be useable. We've also tried similar methods through Adobe Illustrator and ended up with relatively the same results.

The grand majority of our ombres turn out fine, but it happens most consistently with ombres of black-to-white, and one instance of violet-to white, as shown in the images below. These pieces are printed on Tobago spandex. If anyone has encountered a similar problem before and found a working solution, we would love to hear it, as we have been trying to tackle this issue for awhile!