Platform, device version and operating system:
Steps to make it happen again
This is easy to reproduce with a weapon such as Mountain Crusher.
Get in a battle with MC, then click the hero with MC.
On the left hand side, we can see the Brown Gem count.
Then click on the trait or unit icon, and then back to the Weapon icon. The gem count doesn’t appear anymore.
This can also be reproduced with any unit/weapon that shows a gem count.