Leviton slide dimmer switch w/locator light light comes on but doesnt dim

https://www.leviton.com/en/products/6672-1lw

Specs say Dimmable LED lights are fine, so that means your lights are the ones at fault. Although marked dimmable, they are aren't. Swap the bulbs out for another make. Also if you read the FAQ on the lower section of the page, there are secret switches hidden behind the slider. Also interesting to me is that on the top metal fixing plate it shows
LIGHTED OPTION
ON - OFF

Replace it. They fail and and that is not uncommon. good luck

How many wires are on the dimmer switch and what
colors are they ? How many wires were attached to the old switch ?

Wiring is not best suspect.
If all the Leviton devices were installed same time, they may be failing at same time due to lifespan.
For example, ordinary on-off switch is a mechanical device with mechanical parts, and mechanical switches last many years longer than wiring devices that have electronic parts.
Electronic devices usually have standard 1 year limited warranty.
http://www.leviton.com/OA_HTML/ibeCZzpHome.jsp?minisite=10025&respid=22372

Just tripping the breaker should no affect your dimmer unless maybe malfunctioning or wired incorrectly or loose connection. It is hard to wire incorrectly, for there should only be two wires attached to the dimmer? Replace dimmer and make sure wiring is correct if not sure about wiring yourself contact local electrician for your safety. There are very good instructions inside the switch packages, make sure to buy a quality switch, Leviton is a good name I would lean towards faulty switch or loose connection but I'm not there. Good Luck Karen....

Sounds like that dimmer you ruined
You must turn off power when replacing
And test the wires

Look at 3-way drawing in 6633 manual.
Notice that device has to be installed to Hot wire.
Only one of your 3-way switches will have the Hot wire.

Change device with other 3-way switch.
Make careful note of which wire connects to dark-colored screw. This is the common screw.

You posted under Leviton rotary dimmer.
Lutron and Leviton have many 3-way dimmer styles, and both make 3-way rotary dimmers.

I remember years ago replacing 3-way switches with dimmers and having same experience as you. One dimmer has to be ON for the other dimmer to dim.

Later I learned when you replace both 3-way switches with dimmers, you buy a control-and-companion dimmer set. One dimmer is main, and it lets you dim from both locations. The two dimmers communicate with each other electronically. Buy these dimmers at lighting store that specializes in fixtures and dimmers. Ask for most experienced salesperson.

I checked to see if rotary dimmers are made in the companion set. And neither Leviton or Lutron show 3-way companion set rotary dimmers.

1) Leviton spec sheet on rotary 3-way dimmers does not show companion dimmer. This indicates that Leviton rotary dimmers don't have capability of communicating with each other.

2) Lutron has image of 3-way rotary dimmers.
Image shows single rotary dimmer in 3-way & 4-way circuit.
This tells me that Lutron does not have companion dimmer for 3-way rotary dimmer.

if your trying to dim a florescent fixture you need one for those fixtures

Unfortunately, the hum is normal for operation of that type of dimmer at low levels.  Sometimes the lamp filaments will also "sing" a high pitched sound.