In my experience, DevOps Engineers work on maintaining existing code, not creating new code. In larger organizations, there are developers set aside to handle issues arising from day-to-day issues (bug fixes, ad-hoc stuff that operations folks need done) while other developers work on new project (adding new features, creating new projects). A DevOps engineers day-to-day tasks can vary wildly, depending on what happens during the day. However, it should be noted that these folks don't get to do much in the way of creative development. They're just "maintaining", possibly even legacy code or legacy systems.
I've worked in companies that had DevOps teams, and our boss was cool enough to rotate developers every once in a while so that DevOps folks could work on new stuff every now and then.
There are some developers that love to just maintain existing code. There are developers that HATE doing that and would much rather create new stuff all the time.