I am experiencing the same issue.  I have been using the TikTok integration for weeks.  2 days ago the bot flows stopped working.  I tried refreshing the permissions and deleting the connection in ManyChat with no success.  I have submitted a ticket and provided screen shots and screen records with no answers yet.

The ManyChat side is no longer able to tell that my TikTok account is a business account.  Someone on the ManyChat side needs to fix this bug.

I had to change the account for the moment for a new one and it did connect, it is not what I wanted because in the account I wanted to connect is where I had my main content and I had to start again for the moment.

I am experiencing the same issue ! 

Here is a link to the open ticket I have going with ManyChat going back 3 days:

https://help.manychat.com/hc/en-us/requests/290051?page=1

Yea , i have been in contact with the support team for a few days as well. I am hoping they can fix this.

Hi all!

I am very sorry you are experiencing connection issues!

We are looking into all tickets with TikTok team and will be back to you once investigation is over!

I checked the documentation and in my case the problem is that my account is in a  EE. UU. region.
I will create a new account in a suitable region to solve the problem, thanks.

Hey ​@tenloo! Thanks for letting me know! Yes, indeed, unfortunately, the EEA countries are not yet allowlisted but we are working hard with TikTok team to make it possible soon. Stay tuned!