Guild Wars 2

So I manage to get some people help me defeat the Chak Driver however I died at it took me awhile to run back, once I make it back its defeated by I know I hit it with enough damage and got an award chest, do you have to be in the area its defeated to get the mastery point or no?

That’s most likely event participation decay that came with HoT. If you’re not actively participating in an event you tagged before, after a time the game removes your participation credit.
So, it took you too long to return, and the game thought you have abandoned the event, and thus withheld the rewards.

But he received the award chest, so his participation was registered. It sounds unlikely that the game would use different participation timers for chest and mastery point. I’m not sure about this encounter has any distance limits, but I’m sure I’ve WP’d across maps before and still got karma/gold rewards from events I tagged, and I can’t see this as being any different.

It’s probably worth sending in a support ticket/bug report.

onevstheworld.2419:

But he received the award chest, so his participation was registered. It sounds unlikely that the game would use different participation timers for chest and mastery point.

Valid point, i missed that. Then there are only 2 reasons why it might work like that i can think of. Either he got event participation credit for the event due to killing smaller spawns, but was unable to tag the Driver itself, or he had that mastery point already. Now, the first point is a bit iffy, since i was 99% certain that the MP was tied to the event, not to the boss itself

And no, range itself is not a factor, seen people getting that very MP when standing at Rata Novus WP