Cannot publish my solution after removed one

I try to publish my solution for the letter queue task. I have already solved it and published a solution for this problem, but I removed it and now I cannot publish again for this task. I am getting this error "You cannot publish your solution for this task. You might have to solve it first" that doesnt make any sense. Also some times when I hit the publish button it seems like it loading the page to see my publication but nothing happens.

All of the above happen only in this task and only after I removed my previous publication for this task. I can publish normally for other tasks. Is this intentional? It doesnt seems so..

By the way, the reason I removed my publication is that it had the "main" part also published. Why that happens some times? I didn't change that part at all.

Thank you for your time and the awesome site you created.