Hide and show options

[WilliamJYoung]

I'm working on a Power Automate adaptive card (v1.2), I wanted to hide a section, based upon an input selection (e.g. a Yes/No radio button control). I tried various methods (including show when) but there appears to be very limited examples and the only thing I could get to work was displaying a 2nd card, based upon an action. This is OK, but not really what I wanted, as I'd like the control/buttons to hide, once the selection is made.

How should this work?

I had a good trawl through the available resources and some looked like they might work but didn't for me. Any guidance resources would be really useful, thanks
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For clarification: why does this not work (i.e. both TextBlocks show on the card)?:
{
"type": "AdaptiveCard",
"$schema": "http://adaptivecards.io/schemas/adaptive-card.json",
"version": "1.2",
"msTeams": {
"width": "full"
},
"$data": {
"price": "35"
},
"body": [
{
"text": "This thing is pricy!",
"type": "TextBlock",
"$when": "${price > 30}"
},
{
"text": "Dang, this thing is cheap!",
"type": "TextBlock",
"$when": "${price <= 30}"
},..................

Is it a versions thing, maybe?