Darn, that shoots down one theory. You aren’t the only one having this problem but someone else said it happened to them on 7 but not on 8 or 10, so I was hoping that was related. I’m sorry, but all I can suggest for now is to try a couple of things I haven’t heard back on and one other that I found on another troubleshooting site. Here are the ideas I haven’t confirmed as working or not:
Try going to uk.fiverr.com instead of just fiverr.com
Try a mobile browser if you have access to one (not the mobile app, but a browser)
Try creating a new Windows user profile and see if you can get to Fiverr under a brand new profile.
Edit: I’m adding this as one last thing of note. Of the people I’ve seen with this issue all but one have buyer profiles (no gigs) and have no Country listed on their profile. You might try adding your language and don’t use any kind of proxy server or anything that might cause your location to be missing or incorrect.