UF fails when adding Advanced Option

V13.7.1 UF 13.4.1

After adding, and even after removing, a simple validation rule in Advanced Options, the form fails when going to it’s second page (where the rule would have applied) with the error:-

KeyNotFoundException: The given key ‘90a4c335-34a4-4243-a727-a5b6f1766820’ was not present in the dictionary.

The guid is the form’s second page.

The Advanced Option validation rule was only:-

{
  "==": [
    "{password}",
    "{confirmPassword}"
  ]
}

Error continues after the rule is removed, form re-saved, temp folder deleted, site restarted. It’s a 50+ field form.

Any advice or is this a bug worth reporting?

Still an issue. May it doesn’t work on password fields?