I hope you were able to successfully order! Ever since Google Chrome was updated, I have trouble ordering from sites such as Sephora, Ulta, ColourPop, LASplash, Nordies, etc. My boyfriend who is a computer programmer explained some possible technical explanations for this problem. So now I am using Internet Explorer (which I normally avoid like the plague), and I have been having fewer problems. With Chrome, I am constantly being logged out of my account, items disappear from my cart, etc. I was able to successfully place an order for several of the matte liquid lippies on IE (finally! I missed out last time) - I picked up pretty much all of the purple and pink/nude shades (Koala, Trap, Midi, Lychee, etc.).
I don't know if Firefox is having the same issues as I don't have that browser on my computer. You may want to try Internet Explorer if possible. Of course, the problem may be wholly site-related, not browser-related. Good luck!