Attempting to use Paypal express checkout (sandbox) and following debug response


{
"debug_id": "d9d57071e5135",
"details": [
{
"description": "The value of a field does not conform to the expected format.",
"field": "/purchase_units/@reference_id=='default'/amount/breakdown/item_total/value",
"issue": "INVALID_PARAMETER_SYNTAX",
"location": "body",
"value": "xxxxxx"
},
{
"description": "The value of a field does not conform to the expected format.",
"field": "/purchase_units/@reference_id=='default'/amount/value",
"issue": "INVALID_PARAMETER_SYNTAX",
"location": "body",
"value": "xxxxxx"
}
],
"links": [
{
"encType": "xxxxxx",
"href": "https://developer.paypal.com/docs/api/orders/v2/#error-INVALID_PARAMETER_SYNTAX",
"rel": "information_link"
}
],
"message": "Request is not well-formed, syntactically incorrect, or violates schema.",
"name": "INVALID_REQUEST"
}


I've read one solution about adding expression
b[i][b](token)[/b][/i]
to
Prevent Lowercase URL Regular Expression as suggested in another similar post but not sure if I've used proper syntax with expression.

Full field content is:
\bverificationcode\/b[i][b](token)[/b][/i]/