Update
This proposal passed and was queued for execution. Unfortunately, the proposal cannot be executed on-chain in its current form.
For complete clarity, the issue is non-destructive and there is no loss (or risk of loss).
Whilst the calldata was correct, and the simulations passed as expected, the calldata was generated against the blockchain state at the time and did not give consideration to other ongoing executable proposals.
Alongside this proposal, another proposal was in motion (Tally | ENS | Enable Root and Registrar Security Controllers), which passed and was executed prior to this one.
That proposal changed a dependency on which this proposal relies - specifically, the ownership of the Base Registrar. As a result, the proposal as-is can not be executed.
I will re-submit the proposal with updated calldata that gives appropriate consideration to the updated ownership model.