I have a server action that fetches comments from an API:

"use server"

let url = `https://api.xxxxxx/comments.php`

export default async function getComments() {

  try {

    const resp = await fetch(url, {
      next: { tags: ['comments'] }
    })

    const {data} = await resp.json()

    
    return data

  } catch(err) {
    return {
      error: err.message
    }
  }
    
}

I also have a Form.js component which is a client component marked with the 'use client' directive. I use the form to create new comments by sending the form data to another server action createComment.

Form.js

'use client'

import createComment from "@/actions/createComment"
import { useRef } from "react"



export default function CreatCommentForm({addOptimisticComment}) {
  
  const formRef = useRef()

    const submitForm = async (formData) => {

      addOptimisticComment({
        "id": Math.random(),
        "title": formData.get('f_k_page_title'),
        "body": formData.get('f_body')
      })

      
         await createComment(formData)

        formRef.current.reset();

        
    }


  return (
    <div>
      <form action={submitForm} ref={formRef}>
      <input type="text" name="f_k_page_title" placeholder="Title" className="border" /> <br/>
      <textarea name="f_body" placeholder="Body" className="border"></textarea> <br/>
      <button type="submit" className="p-2 mt-3 border bg-neutral-300">CreatCommentForm</button>
    </form>
    </div>
  )
}

createComment.js

"use server"

import { revalidateTag } from 'next/cache'

export default async function createComment(formData) {

try {

    const resp = await fetch("create-api-url", {
      method: 'POST',
      headers: {
        'Cookie': `PHPSESSID=${sessionId}`
      },
      body: formData
    })


    if (!resp.ok) {
        throw new Error('Error creating comment')
    }


    data = await resp.json()

  } catch (err) {
    return {
      error: err.message,
    };

  }

  revalidateTag('comments')

}

When I submit a new comment, it gets saved in the database alrihgt but the comments data is not revalidated even after adding revalidateTag('comments') to the createComment server action. The correct data is only fetched after I refresh the page. What am I not doing right here and how do I correctly use revalidateTag()