Hi there - I'm having the exact same issue. If you look closely you can see those marks on uncoated thicker stock as well. Did you ever find a solution?
Other things I've done so far
I can't seem to prevent those markings from appearing on the coated paper. Keep in mind I've only had 300 prints so far with this printer. This looks like a feature of this printer. It can print on Gloss paper, but it shouldn't as the hardware of the printer will damage the paper.
So there is an issue whenver I try to print on any kind of glossy paper. My prints are always left with what looks like print roll marks where the rollers leave a permanent pressure markings on my prints. They appear on the right and left side of my prints. The center area of the paper do not have these marks. I'm printing on HP Professional Business Paper 52lb 200gsm which is well within the specs that this printer can handle.
Things I've done:
This only happens when I use glossy paper. These markings don't show up when I use regular copy paper or uncoated cardstock. Take a look at the provided photos for some idea of what they look like.