MG 2.1 Album thumbnail problem: getting weird dots on borders


Active member

I have purchased and installed the latest version of XFMG just this morning, on the latest version of Xenforo.
I've set it up all good and nice but after uploading my first album, I'm getting a weird issue on the album thumbnails, see for yourself


The border between images alternates black & white dots, isn't that weird?
I have tried rebuilding the album thumbnails but it's still doing the same.

I googled the issue for a while and searched the forums but I couldn't figure out what's wrong.
Does anyone have any ideas?