I have been facing a recurrent issue with exposure inconsistency on my prints for sometime now.
I am using the Piezography Pro 11 inks system with K5 curves (all my curves have been linearized using the Piezography Pro Tool): I prepare my file on Lightroom, export it as TIFF, process it down to Grayscale with Photoshop and then load it onto Print Tool, applying split tone and Black ink choice through QTR, saving the settings before printing.
I then assess the result and I might apply a slight local correction to my file on lightroom before going through the very same process as above, printing with the very same presets (as saved previously).
I find that in a number of cases the general exposure of my new print will be off by up to 1/2 stop! I insist that I am not changing the Split Tone settings (which would likely affects exposure) or any other preset, apart from the local correction applied on Lightroom. I surely should be getting the very same overall exposure! I often find that it is not the case.