I was wondering could someone please help. I am working on a WordPress website. I have added blog posts and everything was going fine until unexpectedly I start getting the following message. (Side point: If you look at the message, available is actually spelled incorrectly also - AVAIBLE)

Now I have 11 blog posts, separated on the blog overview into 4 per page. So 1st page has 4 posts, 2nd page has 4 posts and 3rd page has 3 blog posts. When I set one of the posts as a draft, I should see 2 on the last (i.e. 3rd) page, but instead I see the 404 error page, even though there should be 2 posts on that page. When I publish the drafted post, everything works fine and I see the expected 3 posts on the last page.
Each of the posts themselves are fine, as I have tested clicking on each one and it brings me to their designated page as expected. But it's just in the main overview of the blogs that I'm having the issue.
This is a major issue as I now cannot add blog posts without this happening at certain time. Can anyone please help me resolve this issue?
Thanks