If I miss the Radiant Slime the first time it spawns, will it appear again?

This has happened to me in a couple of "guaranteed" locations. For example, the radiant spawn point >!in Rainbow Fields behind the feral cave with the teleporter to Ember Valley.!< When I read the description of the location, I knew exactly where it was and went there. Since I was new at this, it's entirely possible that I didn't notice the radiant even if it spawned.

I have gone back many times, and I know I'm in the right place because I've watched a couple of videos. It is definitely not appearing now. Any tips? I've gone at different times of day.