No Skill XP?

Check the Action
Read How to Earn XP for that skill.
Placed blocks, young crops, and some mobs do not count.
Making food does not award skill XP.

Check Your Mode and Level
Creative and Spectator actions give no skill XP.
At the top level, your XP bar is already full.
Check /skills for your progress, even if your XP bar is hidden.

Check the Location
Protected town may block gathering.
Open Exploration, then How to Earn XP.
Check which places count for travel.
That page also shows which ways of traveling count.