SSML/Prosody no longer supported on TTS?

I am attempting to slow down my TTS buy a few percent, and I came across a post on the forum suggesting the use of SSML/prosody tags. They work fine when using the "Speak" action under the device, but when I try to enter them in Rule Machine, the tags are stripped as soon as I leave the text input area.

Is this a bug, or is SSML/prosody intentionally not supported in the Speak or Send Message action in Rule Machine? If it's the latter, how can I get around this?

Are they actually stripped or just not displaying; i.e. if you re-enter the text input area do they re-appear? I seem to recall something similar happening to another type of tags (can't find the thread right now), but it was just a display issue the tags were actually still there.

They do seem to be stripped off permanently.