VoiceOver is not speaking the time correctly on the top of the hour when in 24 hour mode

When the time is set to 24 hour mode, and the time is after 12 o'clock, VoiceOver does not speak the time correctly at the top of the hour.
For example at 10pm, which is 22:00, it should say "twenty-two zero xero".
Instead, it just says "twenty-two".