I can confirm this odd glitch as well with Windows 7 Ultimate 32-bit and Mozilla Firefox 31.0 browser.
When mousing over +Upload, then clicking the option Side-by-side, the upload popup box comes up, but there are no Load parallel image or Load cross-eye image buttons in the box to then choose which type of side-by-side image you are going to upload.
Simply hitting the browser refresh button once usually fixes the issue, but on occasion I've had to hit refresh several times before the issue is resolved and the selection buttons return. I don't recall exactly when I started noticing this issue, it's been happening on occasion for a while now, but it didn't use to happen when I first started using Phereo and that upload option. It's just odd that it seems to be sporadic, and doesn't seem to happen with any consistency to pin a cause on why it might happening.
I've done the usual clearing of all my temp files and browser cache, but it still occasionally happens.
It's a minor annoyance really, but it would be nice to figure out what is actually causing this issue, and find a permanent fix.
Matter of fact, as if right on queue, I just went over my Phereo account, moused over +Upload and clicked on Side-by-side, and got no buttons on my popup ... below is a screen shot of it.
~ Craig ~