Grid Layout not displaying properly

I’m just trying to create a simple grid using the advanced posts block.

The issue is that when I look at the grid in editor it display good. It display a 4 x 3 grid.

When I look at it on the site it display 3 columns on the first row, then 4 columns on the second row and third row. Then it creates a 4th row that I never made to add one more post to the bottom.

So it’s like it takes the fourth post on the first row and creates a 4th row and puts that post on the bottom.

If I clear the cache it fixes the problem temporarily.

Not sure what’s going. Any help is appreciated.

Good layout:

[post1, post2, post3, post4]

[post5, post6, post7, post8]

[post9, post10, post11, post12]

 

Bad layout:

[post1, post2, post3, blank]

[post4, post5, post6, post7]

[post8, post9, post10, post11]

[post12]