Having installed v3.1.0 on a test logbook, I find that I can browse and select a file, but when I click on the "Upload" button, I get a pop-up message from the browser asking me:

"This page is asking you to confirm that you want to leave - data you have entered may not be saved."

The stay on page does nothing, the leave page option does what one expects from elog - that is the attachment thumbnail is generated etc. 

I guess this is something to do with the drag and drop feature, but wondered if others have this issue or whether it may just be some mystery setting of the browser (firefox).