As topic, I’ve tried 3 days, with all the way I could think to complete the task, but just not working.
I’ve re-installed the game, finish in single game / mutli AI game., I even wait AI collected 5 Relics, then destroy it’s monastry and took all 5 relics to my monasty.
But, still not working 
Hello @tempest0104
Are you logged into Xbox Live?
You can try creating a scenario with relics, monks and monastery and then playing this scenario as a custom scenario in a Skirmish game.
got the same issue, i am logged in (got that log-into xbox reward instantly)
cheats are disabled, tried with some mods on (usually play w/o any but the game seemed to enable some by itself) then tried with all off…
I have tried:
scenario editor, placed monastery and 5 relics + monks, pressed “Test”, delivered all 5 into monastery (this has worked in the past) - unsuccesful
normal skirmish VS AI, all map visible to find them faster, no cheats allowed, collected 5 - didnt work
Tried what people on steam said, single player campaign - Asia - Balalvaila whatever his name is, SECOND mission defend the monasteries, you start with 5+ monasteries that hold one relic each- (supposely worked for someone) didnt work again…
also tried what Felizion89 said
realllllly annoyed by this, when I wanna start collecting something in a game like cosmetics and I have to become some sort of software troubleshooter guy and even it wont work.
As topic I tried many times but i can’t unlock challenge too
So after the bugged Mongolian & Barbarossa events this once again prevents long-time players from participating and completing vaguely interesting event missions for mods that will be freely available in the workshop plus some player frames my grandma couldve knitted herself, but I wont be able to add anyways (read: FOMO).
Gonna get your shit together before you sell aoe2 for the 3rd time on steam, perhaps?
Just create a custom scenario with 5 relics and monks, then play it in skirmish mode as @Felizon89 said. Wait for 200 years to pass and after the game is finished with relic victory you will complete the challenge. This was worked for me.
Did this 2 times now, once with 6 and then 5 relics, doesnt work for me.
Same here, doesn’t work. Tried all suggestions here so far
Same here have tried multiple ways, relogging compelting solo, and with friends but the gather 5 relics just does not get ticked.My gf got it first try but for me 5+ games with 5 (exactly 5 relics) still nothing a couple games with 8 relics still nothing, it just does not register.
Had these issues during Mongolians and Barbarossa events aswell. Since then (and before), Ive done pretty much every single event without any problems and thought, hey they seem to have fixed something! But not really, I think this is a server-side or account-based problem and they just dont get enough feedback here to investigate it or they cant reproduce it since only a small portion of players experiences this bug.