Hi,
I'm on 5.6.5. I just solved the problem using the empty markdown visualisation, thank you.
(FYI The action causing the problem was: say my top row of graphs had just two graphs which were 1/2 the available width each, and underneath I had a row of three graphs 1/3 the available width each. If I resized the top two graphs to make them also only 1/3 the available width wide, a graph from underneath would slide up to fill that spot.)