How to fix chipping/cracking mortar?

[atibaldi]

Hello, newbie here! Can someone provide some advice on what product to use to fix these areas where I’m losing mortar above the tile? Also some guidance on how to fill it in would be helpful as well.
thank you!

 

[ajw22]

Show us your expansion joint.

If you do not have a good expansion joint the coping will move and that area will continue cracking.

Expansion Joints and Coping - Further Reading

www.troublefreepool.com