Maybe stepping outside of the box a little, but using those drops is pretty inaccurate. They work, but really hard to read. I would look at getting a digital meter.
Anyway, you’re just as easily locked out due to a ph condition. It’s completely possible to have nutrients available, but plant not taking them up from ph range. Feeding when plant won’t consume won’t help much.
Also, that could easily be a cal/mag issue as well. I’d have to go back and check the nectar line, but it’s suppose to be calcium based. Another thing that points to potential uptake issue.