Thanks for that, we currently reviewing how the search works in that select box as its not great.
For the time being would it make sense to use a taxonomy term to select those posts in the sidebar ? Whilst we figure out what is happening ?
We want to select posts manual. So taxonomy term selection on category is not what we prefer. Maybe select based on tag? Is this option? The best option for us is when we manual select posts.
We will make an update soon that will allow search by ID, which will be more reliable then title strings, but we will also try to improve the title search 🙂
You can use any Taxonomy, so just add the Taxonomy Parameter to the Query Loop and select Tags.