As the subject says, right now have only tried with Pete, but have all the items, click to complete the quest and it gives me the Gateway Timed Out error screen. If I navigate to a different screen, the quest shows at the top of the screen with everything "turned in", but still an option to complete the quest. Clicking complete from there seems to just give an infinite loading symbol in place of the complete button before eventually giving me a Gateway Timed Out overlay, instead of a full screen like through the quest page.

Just refreshed Pete's quest page and it gives me a "Quest completed successfully!" bar at the top, but doesn't show any quest rewards below, instead going straight to the screen to start a quest as if you've just navigated from the main quest hub. That being said, checking from this forum edit screen (which wasn't refreshed/navigated to before getting the "Quest completed successfully!" message to open another Subeta tab does indicate my sP went up, so reward was given successfully, just something messed up for completing the quest normally.