I second all that Chris said in her post above. It's important to get some data for the evening cycle, even a 'before bed' test would be helpful.
And it can take time for a cat to become regulated. Some regulate quickly, some take longer, some never get regulated, some go into remission. And each cat takes its own sweet time to do what it's going to do...
A couple of thoughts. I think your kitty may have some 'bouncing' (rebound) going on.
When the blood glucose drops too low or too fast (or both) the body can see that as a threat and release stored glycogen to raise the level. 'Too low' doesn't necessarily mean 'dangerously low'; bouncing can be triggered even when a cat's blood glucose drops lower than its body has lately become accustomed to. Bouncing is pretty common...
The body can also release counter-regulatory hormones to cause temporary insulin resistance. It's a protection mechanism. And when this happens what the caregiver usually sees is high 'flat' (unmoving) numbers that seem unresponsive to insulin.
If you look at your kitty's morning cycle yesterday, for example, those numbers are flat and just didn't budge. The same happened on 13th July, and to some extent on some other days too. That 'can' be an indication of bouncing.
Another indication of bouncing is high numbers following lower numbers. If you look at the 14th July, the numbers rise quite quickly toward the end of the cycle. There is an even better example of the same on 25th June.
...High numbers toward the end of a cycle can also be caused by the insulin not lasting long enough in the kitty's system (numbers rise when the insulin wears off) but I'm not seeing any actual evidence that your kitty is getting short duration on the Prozinc, so bouncing seems more of a possibility to me...
My 'best guess' - on the information available - is that the dose is a bit too high, and that the numbers may even out a bit more if the dose was reduced.
...I do wonder how it would have been if your kitty had stayed a bit longer on the 0.25 unit, because you only tried that for a couple of days, and on some occasional shots thereafter...
Prozinc can also be quite sensitive to dose changes, and can sometimes take a few days to 'settle' into a new dose. That 'may' also be something that has added to the erratic nature of the numbers.
If you can get a pm cycle test or two routinely that may shed more light on the situation, as it will fill in more jigsaw pieces in the puzzle.
Eliz