So I know there are some threads on the bumper fitment issue but it didn’t completely solve mine. Attached is the brief video I made on what else I had to do to fix it.
I had my bumper popping out in the *exact* same spot as yours (passenger side under the marker light). Replaced both of the plastic pieces (side and under headlight) and still had the problem.
I fixed it differently though. Your method is definitely less intrusive than what I'm going to propose --
If someone attempts JetLife's fix and doesn't succeed, you can (try) take a Dremel-like tool and slightly (**slightly**) widen the holes in the bumper that catch onto the plastic tabs below the marker light. I think in my case, the notches in the bumper were slightly off and wouldn't catch on the tabs of the plastic piece below the marker light. I think I took maybe .5mm out of those holes that the tabs engage. The bumper just wasn't catching those tabs in my case. I suspect this is the same issue with two different fixes.