Promoted Links - When centered, lose tiles on re-size

So I'm running into an issue with a promoted links web app.

I've got 7 tiles in my promoted links and I've added the following style to the source to get the app to center.

.ms-promlink-body {
width:auto;
text-align:center;
display:inline-block;
}

.ms-promlink-root {
text-align:center;
display:inline-block;
}

This works OK on a screen that's wide enough so you don't get the scroll bars appear;

But when the scroll appears, the scroll 'works', but the tiles that should be off-screen are instead entirely invisible;

When I remove the style and have the links default to their right-alignment, everything works fine. I've tested this issue and it happens on Chrome, IE, Edge and Firefox.

Has anyone else run into this? Is there something I'm missing in terms of the CSS style I'm applying?

Thanks,

Matt

*I would post screenshots, but I've not been 'verified'...