Gallery layout inconsistent

I’m using Meow gallery throughout my site. On this page: https://www.williamstewart.me/venice-revisited-calendar/ I’ve got two galleries, the first contains 16 images. The short code is: [gallery link="file" columns="4" ids="7056,..."]

The gallery displays as follows:
Row 1: 4 images
Row 2: 4 images
Row 3: 4 images
Row 4: 2 images
Row 5: 2 images

I was expecting to see 4 rows, each with 4 images.

ALL images are the same dimensions, so I see no reason for breaking up the final 4 images into 2 rows.

I see this behaviour consistently throughout the website, so it is intentional, but I would prefer it to be different.

Is it intentional? A rounding bug?! (Seems unlikely). Is there anyway this can be overridden if it is?

Thanks

William

The page I need help with: [log in to see the link]