What you see under "My Posts" besides your own threads is actually thread(s) marked as "Featured" due to their important content, which (threads) will always be at the top of al the top bar filters. This is not a bug - this is the EasyDiscuss extension logic.
The filter 'my posts' appears not to be functioning correctly in the Joomshaper support forum.
The joomshaper support forum is the place to look filtering by my username "My Posts" as shown in the screen capture. Another user post is included in my filtered view "my posts". This is not my post rather a post by another user, nor is the post by the other user related to any of my posts as a reply. The post by another user should not appear in "my posts" view.