Sorry for the delay in getting back to you. In the middle of a large upgrade and it’s not going well.
I eventually sidestepped this issue. This instance of Rancher had been about for a long time and been upgraded from around 0.34 and had been played with a lot. We also had errors relating to long destroyed hosts. I built a new Rancher from scratch and migrated the hosts and redeployed everything. Not ideal but at least we’re ok now.