Posts include HTML tags

[johnthan]

I got a new version and after setting up the forum, the editor appears half and the post includes HTML tags.

I even tried to see if any plugin was causing it. Even after deactivating the plugins the same happens.

If it is the editor, then how can I make it to fix?

The editor appears half:
   

The post appears with HTML:
   

[HLFadmin]

This has happened before.
https://community.mybb.com/thread-232255.html

What did you do then to resolve it?
Follow the steps as outlined in the link in effone's post.