Columns distribution problem with Visual Composer

I’ve spotted an issue with Visual Composer not distributing correctly elements according to “Columns” setting when using a (Woocommerce) Product Category element.

If I set it to 4, it will distribute it as:
A B
C D
E F

instead of:
A B C D
E F

I’ve checked the generated html and it’s setting a css class “first” and “last” to elements in the grid.
A, C and E are marked as “first”.
B, D and F are marked as “last”.

Any idea of how to fix this??