Skill disappear from bar and became unusable

Hello.
I'm sick of this bug guys.

Idk how, idk why... sometimes (already happen to me at least 4 times) some skill gems became unusable.

the skill disappear from the bar
u cannot re-add to the skill bar
u have to re-forge another identical skill
re upgrade the level of the skill gem
re upgrade the quality of the skill gem
re upgrade the number of gem's sockets

waste of time
waste of currency


please fix that.