More than likely you are back to what Al stated and I was hinting at with my questions: they want to confirm depth of penetration.
In case you, or someone reading this doesn't know, your fraction on the right in the parenthesis, '(5/8)', is the weld size/thichness. The fraction on the left, '3/4" ', is the depth of bevel. So, either your plate is already 3/4" thick (which we know from your OP that it is actually 1") and at an angle (30-60°) that gives you your bevel, or the plate is at a T and needs to be beveled for 3/4" out of the 1" thickness. Then, the engineer and/or detailer has already factored the Z-loss and knows that what ever process is being used will not be dependable, for strength calculations, to penetrate all the way into the root, thus, they give it a 1/8" less weld size than the bevel depth.
So, your UT tech is trying to make sure that the PJP's are indeed getting down to the 5/8" penetration called for on the plans.
Additional note: if there is no weld symbol included for an addition fillet weld after the PJP then the weld only needs to be flush with the edge of the plate. This includes skewed fillets on the obtuse side (larger than 90° angle). The weld size is the penetration, it has nothing to do with any additional weld reinforcement beyond the full weld depth of being flush with the plate.
Have a Great Day, Brent