imho its more likely an obstruction during printing.
To the best of my knowledge and information that particular printing is done using "offset printing" method.
Generally speaking in an offset printing process unless there was some obstruction on the printing substrate (i.e. the polymer sheet) any other obstruction would still result in some form of inking.
For example if there was obstruction on the plate that provides the impression then the thing that creates the obstruction will receive the ink and that ink will get transferred to the blanket which will in turn get transferred to the paper. In fact it will be worse because the obstruction will receive full ink. One exception to this is if the obstruction itself is so precisely averse to receiving ink on it.
If there was an obstruction on any of the blankets then the ink would still get on to the obstruction and then get transferred on to the substrate.
The classic manifestation of an obstruction is generally a hickey which shows up on the substrate typically in a doughnut form. However void hickeys are possible and perhaps could result in a non inked area. Most modern printers will have some mechanism to automatically remove hickeys or at the very least these hickeys will occur for a certain number of prints at the most.
What I am reporting is something that has been observed in precisely the same location and spanning many thousands of imprints.
Based on my knowledge of the offset printing process I am not sure if there is any other type of obstruction that would create such a precisely located area of missing ink over that many number of imprints.
If you have any further insight it would be appreciated if you can share it.
Thx.
