Issue with a custom tool

[Toolfolks]

I have the following custom tool:
add_event
Get the event details
Property Type Description Required
dateTime date dateTime Yes
details string details Yes
duration string duration Yes

const fetch = require('node-fetch');

const url = 'https://hook.eu2.make.com/xxxxxxxx';

const options = {
method: 'POST',
headers: {
'Content-Type': 'application/json'
},
body: JSON.stringify({
'dateTime': ${$dateTime},
'details': ${$details},
'duration': ${$duration}

})

};
try {
const response = await fetch(url, options);
const text = await response.text();
return text;
} catch (error) {
console.error(error);
return '';
}

In the openAI Assistant this creates:

{
"name": "add_event",
"description": "Get the event details from the client and post the details.",
"parameters": {
"type": "object",
"properties": {
"details": {
"type": "string",
"description": "details"
},
"duration": {
"type": "string",
"description": "duration"
}
},
"required": [
"details",
"duration"
],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}
}

When I save the tool with all the required options ticked and come back to it the required tick on duration is unticked.

I have restarted the pc but the issue remains.

Any ideas why this would happen. I have tried delete the get_event function in the assistant but it get created again but wrong.