I installed & activated Tweetily in the hopes it would fix this issue from Tweet Old Post, but unfortunately it doesn't.
I currently have 13 pages of posts/pages on the Excluded Posts page. I can select posts from page 1-3 without any issues. However, when I go to page 4 to select the posts to exclude and click the "Exclude Posts" button the excluded posts get overwritten with the posts I selected on p4. So the selected posts to be excluded from p1-3 are gone again.