Q.Wilting cucumber leaves
Hello!
My cucmbers have been thriving all summer and have finally started to bare fruit (yay!). Yesterday all of a sudden I’ve noticed most of the bottom leaves and a few higher up have just gone and wilted, and have started to die. Most of the online sources I’ve come across assume bacterial wilt to be the primary cause of sudden leaf wilt, however, I’ve seen no evidence of a nasty little cucumber beetle and when I do the bacterial wilt test of cutting a wilted leaf near its base to check for sticky string fluid, there is none (leaf and stem seem to be normal except for the wilt). It’s been average summer temperatures lately, with a few overcast/rainy days, but watering has been fairly normal.
I have both the pickling and lemon cucumber variety, and the lemon variety seems to be affected more. Some spotting noticed on some of the upper leaves.. unrelated? Any suggestions?

Some wilt on the leaves can be common during the heat of the day. Plants recover in the evening when they cool down.
Make sure the soil is evenly moist, and that it is well draining.
If you see no signs of pests or markings on the leaves, I would not suspect disease.
https://www.gardeningknowhow.com/edible/vegetables/cucumber/bacterial-wilt-cucumbers.htm