How to Fix the Glow Not Showing Up or Looking Wrong
First Checks
If ores look normal, the pack is probably not actually active. Open your resource packs screen and confirm it sits in the enabled column, above any pack that also edits ore textures. Two packs touching the same textures will fight, and whichever loads last wins. Also confirm you are looking at a vanilla ore — modded ores and custom blocks will not be outlined.
Common Causes and Fixes
1. Another resource pack overriding ore textures: move this pack higher in the list, or disable the conflicting pack.
2. Shaders or other visual mods altering block rendering: temporarily disable them to see whether the outline returns.
3. A partial or corrupted download: re-download the pack and replace the file.
4. Wrong pack for your game version: texture formats change between versions, so use a build matching your game.
5. Edits you made yourself: revert to a backup if your modified textures broke.
After Changing Anything
Reload resources with the in-game reload key instead of restarting, then walk to a known ore and check the outline. If it still fails, test with only this pack enabled to isolate the problem.