I believe WashougalWonder has you on the right track. :jointsmile:

A flush with properly ph'd water wouldn't hurt, but do not return to your watering/feeding schedule till the soil dries-out. Skip a watering or a feeding if necessary, but let your medium dry between waterings/feedings. Consistently saturated soil causes a variety of issues.

ProMix HP pdf
Promix High Porosity is buffered to a ph range of 5.5 to 6.5ish. This is pretty low for a soil based cannabis grow, so watch for signs of lockout. The buffering of most peat-based soils last around 6-8 weeks or so, after which the ph will dive to the highly acidic side. Nutrient lockout happens when above or below the proper range. (6.3ish to 6.8ish)
When was the last transplant into fresh soil?

Before making any ph corrections, understand that you can't use tinted (runoff) water to get your color-coded ph results. The tinting will skew the test results, so likely your runoff number(s) arent all that accurate.

For the nutrients:
I've never used Advanced Nutrients, but I'm guessing they are similar to most other nutrients in that:
Grow and Micro during growth stage, (per their weekly instructions) Micro and Bloom nutes throughout flower, (per their weekly instructions) and start the Big Bud half way through flower as well. But go easy on the Big Bud till you get the hang of adjusting your nutrients. Additives often kill when overused.
Have you checked the AN web site for their online nutrient calculator, or whatever it is they call their weekly feeding schedule? Check online, then check the bottle. If they differ in quantities or dosages, use the online numbers. Sometimes the bottle directions that are given asume you are using it as a stand-alone product.

For better pictures, adjust your camera's white balance.