As far as I know, Fiverr doesn’t work well (and never has) on iOS products unless you just use a chrome browser. Support says that Fiverr is optimized for Chrome which appears to be accurate. I have the iOS app and it sort of works half the time, but I have to keep chrome installed on my phone as a backup plan. Safari doesn’t work with Fiverr for me, though I have that trouble with Safari and other things so I rarely use it. The Fiverr Android app isn’t actually very good either and there is pretty much no support for Windows based mobile apps or browsers.
There are bugs in both iOS and Android apps, but neither app is useful for dealing with orders, just for answering messages. These have existed as long as the apps have been out, so I am not holding my breath for a fix. Since optimized Fiverr on Chrome running on a desktop has some bugs too, I would imagine those will be the priority before they ever do anything with Safari or either mobile app.