Anyone having this issue of not being able to upload files to Fiverr as of now?
Mod Note: I have heard that this is a problem for a number of people including myself.
With something like this, always try clearing your cache/browser history but on this occasion it seems like a bug that is site-wide or affecting a lot of people at least.
Deliver via Dropbox or Google Drive and include a note for the buyer to say that Fiverr is not allowing uploads and that this is the suggested resolution for now.
If necessary, direct them to this thread. If you are late with a delivery because of this issue, contact customer support.