Why won't SPOTLIGHT find a name?

[ruffy]

If I search hercules in Spotlight,
looking for this file:
_hercules-3.07-snowleopard.dmg
it does NOT find it!

Even if I enter name:hercules
it won't find it.

How come?
In my Spotlight preferences, everything is checked off.

(I'm running 10.13.5 on a MacBk Pro)

 

[ruffy]

I saw someone's suggestion to run
sudo mdutil -i on /

I then again searched "hercules". Again no find.

I then ran Disk Utilities' "First Aid". It said all's okay.
I searched again and got this:



Yet, when I THEN actually SHOW ALL IN FINDER:
voila!



Now I remain puzzled why -- only in Finder
and
what I did that really changed things.

Anyhow, it kind-of works now (so long as I look for it in Finder).