"Crashes" in that when a file is selected for uploading, in this case on an iPad, the web page blanks out and the browser (Safari) automatically refreshes the page, resulting in no file being uploaded and the loss of whatever text was typed in the message box.
I don't know if that's the case with all mobile devices or inherent in the mobile format of the site, but it is on the iPad with Safari.
On an unrelated note, and this might only concern proxies, sometimes the block bypass fails to show up, even on desktop computers. Sometimes a bypass shows up but submitting it results in "Connection failed.". These proxies work fine on other sites.