No checkbox in content pages

Dear Phil,

I just downloaded your plugin yesterday and it’s exactly what I was looking for.
Unfortunately, the checkbox doesn’t appear on the content page I looked at pages and post and it’s the same for both of them, no checkbox.

I think it’s happened because I was just updated to the latest version of WP.

this is what I see in my posts: https://www.screencast.com/t/D60NMcD6tf6

I hope you could help find a fix for this issue.

Thank you,
Aviv