Samsung SM-T387V Galaxy Tab A digitizer or LCD faulty?

Can a digitizer be faulty in “dead spots”? Recently replaced the digitizer for a customer and it works perfectly for 7 of the 8 vertical inches. When you get to the bottom row where the back, home and runnings apps virtual buttons appear - that area won’t respond to any touch commands. All else on the digitizer works fine. Or is it a possible underlying LCD issue?

ETA: the virtual buttons for back, home and running apps work fine if the screen is rotated, but that “dead” section still won’t respond to scroll swipes regardless. But at least I have a temp work-around to closing an app, you just have to rotate the screen each time.