The way you have set up the pairs in your question does not make it entirely clear if those with the same LNAB are those to be merged - or if there is one other profile lurking in the shadows for each of them. However, I took a look at the two Robinson women, who were indeed "Clear duplicates".
I had the same "already in progress" message when I tried to merge. There are farly often questions about these "stuck" merges. I do not know what the bug is, and I think staff is aware of it.
But as an ordinary user you can "unstick" it yourself, by first setting it as a rejected match, then removing the rejected match - and finally proposing the merge again.
I did that with Ms DeSilver, born Robinson and the merge went through. If you do this with the three others you'll get the hang of it.