What flavor of files are you sending, CMYK or RGB?
To what are your Rendering Intents set? I printed for twenty some years using exactly one, as in one, profile. An Oracal 3651G profile, 8 pass if memory serves, from Oracal for virtually all media, with one notable exception. I modified the profile in this way:
Change all rendering intents, except Bitmap, to "No Color Correction", or "Saturation" if "No Color Correction" is unavailable on your tackle.
Change the Bitmap rendering intent to "Perceptual".
Change the dither and gradient algorithms, if available, to the highest possible setting.
Send all bitmap objects as RGB, not CMYK.
Send everything else as whatever color space it happens to be.
This setup has, for me anyway, has yielded the closest to what you see is what you get as I've ever had.
Your mileage may vary.