No explanation for sprite refusing to mirror. (x2 .capx)

My last thread was more tailored around something else I was trying to accomplish, and now that I've delved deepr into the error I've found the underlying issue. I totally scrapped my bugged project and started fresh, yet here the problem persists again.

I have made two instances of a simple setup. A sprite mirrors itself once it's "enraged" from seeing the player via LOS.

Even though both setups have the EXACT SAME settings for the sprite, one absolutely refuses to work, and I'm at the end of my patience for troubleshooting this.

And here is the .capx I made with the exact same settings, except this time it works! Why?

(The Working version does not have a Custom Movement behavior on the enemy, but if you add one with base settings and don't touch it, which is the same for the one in the non-working one, it still works.)

It's imperative for the non-working capx to work, because I already remade all of the numerous abilities, additional enemies, and so on and I need that version of it to work. I've deleted all of them in the capx for protections sake, and to prove that nothing there was actually affecting this bug.

Interesting. The line of sight looks for a clear path from the object's origin point. In the first capx the origin of the Enemy is at the bottom and it's overlapping the ground so the ground is blocking the line of sight.

Amazing work detective, the problem is solved and the day is saved.