Did you say there are tomatoes in there with the beans because I couldn't see them....
I'm thinking it's the landscaping fabric. I suspect you used it to line the bottom, yes?
By now the beans probably have FILLED the available space with roots. If there was no barrier, the roots would have grown down, out, and below the surrounding grass roots which are shallower.
Depending on where you are in NJ, you would have been getting plenty or rain or have been starting to feel the drought coupled with the heatwave. (I'm in the area storm clouds go AROUND, raining everywhere else BUT here
) If you have not been watering deeply, the surrounding grass would have sucked up all the available moisture on the upper level.
PH -- 8 seems high but I think beans can handle somewhat higher pH in the range. You could try mulching with pine needles, crushed pine cones or pine bark. The mulch will also help maintain the soil moisture.
My pole beans start to yellow from the bottom, too, and get spotty -- some kind of fungal issues that I haven't bothered to ID, because this happens slowly and the upper growth outruns the lower leaf loss. I do spray with milk solution along with other stuff if I have extra.
...btw... Mine have only recently started to bloom -- maybe just in the last week. We had a weird cold snap in the beginning of June that delayed them I think.