Get four columns on site although preview show the chosen three

Hi there!

After the latest update were my galleries suddenly only one or two columns wide instead of three. I use the Responsive image Gallery as I want a symmetrical gallery with square images. I changed the thumbnail size until gallery preview jumped to three columns and update… but now I have four columns on my page! I’ve tried every which way to work around this, what do I do wrong??? I can get three columns in the masonry but that’s not the layout I want. Also the resolution of the gallery is really really bad! What do I do?
Thanks! This is the only gallery I’ve used for the past few years and I love it, don’t want to change if not necessary…

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