Hi Eric,
Based on your images I have the idea those are scans from BW negatives. Am I correct? I have bumped into similar artefacts with poorly scanned or processed images from clients (i.e. trying to get too much detail out of the shadows, scanning too dark or too bright and adjusting that in post-processing, ...).
The grain on those prints appears particularly sharp and I have the impression you have a few sharpening artefacts going on due to oversharpening. In my experience oversharpening can indeed lead to banding. You could try printing the same image without any sharpening applied to see if the banding persists.
Printing through QTR with dedicated BW inksets can yield such high fidelity that prints sometimes reveal issues that are very difficult to spot on a computer screen. Even more so if that screen is a laptop screen or an average desktop monitor.
Let me know if this helps.
Kind regards,
Dieter
