So does that row action remove the extra div you had added to the table footer?  Maybe?   Ooh that’s rough…

My guess is that you have some css that is not working correctly.  If you inspect the element do you see any differences before and after you do the row action?  Do you see any differences between this table and other tables with summary lines?  

That’s where you start digging…  Enjoy! 

I have no css on the page.