I’ve got good news. I ran dnf install R in two containers, fedora:28 and fedora:29. In R, install.packages("dplyr") fails in the Fedora 28 container on my machine (AMD CPU) with the same error you’re getting. But in the Fedora 29 container, it works!
So if you can upgrade to Fedora 29, you should have a working R again. I don’t know if it’s worth opening a bug in Bugzilla since it’s working on 27 and 29 but failing on 28. But if for some reason you can’t upgrade to 29, I’d say go ahead and file the bug.