They look to me to be a little further along than just 4 weeks of flower, that last pic looks ready to harvest (just judging without seeing trichs close-up).
No matter what happens here in the coming days, it looks like you'll have a nice harvest.

The only thing that looks peculiar to me is the runoff pH, you said it's coming out at 5.4. That would mean your medium is that low or lower to bring your water down that low. Lockout will happen just as easily at the low end as the high.

My 2 cents at 1 a.m., hope this helps some.