Originally Posted by
Anarchial
Like Anarchist already said it might be because lag spikes and then coming to normal before you see it.
Here is what you could do to verify:
1)Use the skill
2)As soon as you release the skill button, go to menu to check the ping.
3)Stay on the menu page and check if for even a sec you lag or not.
It is imperative to go to the menu to check the ping as soon as you release the pack skill.
And if you still see that your ping is fine , you can do another thing to check.
Use the health skill while standing still. Does packs still fail most of the time?
If you did the above steps and still didn't get anything, I would suggest writing a report and sending it to STS. But with all the current bug list it might take some time to look into