I'm connecting voiceflow to an OpenAI assistant and keep getting a 400 error.

Anyone know what I'm doing wrong?
I've configured it to send application/json, but VoiceFlow seems to be sending multipart/form-data.

This is the error I'm getting:
{
"error": {
"message": "Unsupported content type: 'multipart/form-data'. This API method only accepts 'application/json' requests, but you specified the header 'Content-Type: multipart/form-data'. Please try again with a supported content type.",
"type": "invalid_request_error",
"param": null,
"code": "unsupported_content_type"
},
"VF_STATUS_CODE": 400,
"VF_HEADERS": {
"alt-svc": "h3=":443"; ma=86400",
"cf-cache-status": "DYNAMIC",
"cf-ray": "87139ac93e0405a0-IAD",
"connection": "keep-alive",
"content-length": "354",
"content-type": "application/json",
"date": "Mon, 08 Apr 2024 16:23:55 GMT",
"openai-organization": "[REMOVED FOR PRIVACY]",
"openai-processing-ms": "87",
"openai-version": "2020-10-01",
"server": "cloudflare",
"set-cookie": "__cf_bm=KoRE3fyY_kVaMJrNAg02PUSrWHA8AcfCE3vgQ3jcJaw-1712593435-1.0.1.1-Lajw.33VxXgd89VvEX81M4sB_cAiQ06.q7XdBgCTHNrEpHHeywYvK34ij.7njz2MAELWauKxHirI62k0hfpn_g; path=/; expires=Mon, 08-Apr-24 16:53:55 GMT; domain=.api.openai.com; HttpOnly; Secure; SameSite=None, _cfuvid=FDK3kLtCkqw.YGwdbaFqTdPjxUvQEZw2QtsiPVz.Wzo-1712593435240-0.0.1.1-604800000; path=/; domain=.api.openai.com; HttpOnly; Secure; SameSite=None",
"strict-transport-security": "max-age=15724800; includeSubDomains",
"x-request-id": "req_f92acce30e11360862e53ec1b0b24c99"
}
}