This thing is a mess. My alt got the pvp quest half an hour ago with 1hr 21min on the countdown(so 2 hour duration?) having obtained the Antenna Component from a potd 9 hours ago. No pvp quests in between according to event history.
Here, I actually just had the pvp quest pop up 15 seconds before its start(1 hour duration) and right on the dot of the hour too. I saw I had obtained the Antenna Component from the previous potd, scrolled around PIMD and the pvp quest popped up. Me no like the inconsistency in duration...I want two hours every time LOL
My current theory which I also tested on alts seeing what you mentioned:
If you receive the 50 PVP action task and speedrun it to get the box, the task won't retrigger even if you have another antenna in your inventory until 2 hours later.
(e.g.: 1PM 50 PVP actions task with antenna in inventory. 1:30PM I got the activated transponder, access card, then box. 2PM: another antenna as misc party drop afters. 3PM, another 50 PVP action task triggers with 2 hrs to complete.)
If you DON'T have the antenna in your inventory after you've completed your last task run, you won't re-trigger the task even if 2 hours have passed from the previous run. So it looks like you might need to get the antenna FIRST.
(e.g.: 1PM 50 PVP actions task with antenna in inventory. 1:30PM: has activated transponder, access card, then box. 5PM: finally new antenna drop. Simultaneously a new 50 PVP action task triggers with 2 hrs to complete.)