Balancer completed but one drive is full

[Cwobbles]

So, I removed an 8TB drive and replaced it with an 18TB. Then replaced another 8TB with another 18TB drive. 8 now have 2x8TB drives and 2x18TB in my home server. The strange thing is that with a balancing operation complete one of the 8TB drives is almost completely full, despite a setting saying should not fill more than 90%. Pics attached. The drive capacities are reported incorrectly too unless hovering over the individual drive details.

Thoughts on how this can be resolved?

[Cwobbles]

As an addition to this I removed the D: drive from the pool and opted to have files duplicated during the process. I then added the same drive back and ran a duplication check and it reports pool duplication to be great, fully green. Yet the readded drive just reports other data with no unduplicated or duplicted data on it. Basicaly the pool is not balanced across all four drives. How can I force it to balance across them? Having read some other threads it seems this is more or less expected behaviour. So I'm now left with one 18TB drive with a formatted capacity of 16.4TB showing a capacity of 19.2TB in the pool and showing 12.2TB free when in fact there is only 7.33TB free. Is this normal too?