Invalid value for key: AllowedKernelExtensions

G'day, I'm getting this error trying to whitelist allowed kernel extensions:

```
Invalid value for key: AllowedKernelExtensions in payload domain: com.apple.syspolicy.kernel-extension-policy of type: manifestsApple

Value: Optional(["MLZF7K7B5R": ["at.obdev.nke.LittleSnitch"]])
```

Any advice on how I should change the input here or is there an issue with the validation?