Automatically set a multi-choice field value based on text

[Gergana.Damyanova]

I'm doing an automation that should set a the value of a custom field based on some text that is dynamically extracted.

I can't get my head around how to update the value of the field.
The key of the project is extracted correctly and is present in the multi-choice options, but I don't know how to select the option that matches the text from the smart value.

Any ideas?

This is how I do the update:
{
"fields": {
"customfield_10453": {
"value": "{{issueProject}}"
}
}
}

The above doesn't work, however with a hardcoded value it works
{
"fields": {
"customfield_10453": {
"value": "MC"
}
}
}