Addon Version
10.2.21-retail
You can get this via running /dominos version in game

World of Warcraft Version
retail

when I log into any character the empty action bar buttons are hidden. I have to go into options, untick "Show Empty Buttons" and retick it. this happens every time I log into any character

I have both. I haven't changed anything but now it's remembering when I change it and relog

Do you get this with just Dominos + Dominos Config enabled? One possibility is you have show empty buttons checked globally, but have it unchecked in your bar's context/right click menu.