Problem: Only 1 thumbnail in a row

Hello!
I’ve got a problem with Maskitto Light – I see only 1 thumbnail in a row, although in WYSIWYG I see 3 of them. Is it configurable? Do I have something wrong?

To see my problem, you can go to: https://zapachklasyka.pl/2015/09/6-praski-rajd-pojazdow-zabytkowych-fotorelacja/