Couldn't purchase Archangel's Staff after I died at ARAM

​After I died, I couldn't purchase item(Archangel's Staff) at ARAM - French Maid Nidalee.

I was still at base after respawned from death, wanted to upgrade my tears to Archangel's Staff, I had more than 1100 gold to buy it, but the buy button was gray. I didn't step out from the base after I respawned.

It was at 11:58 game time after I respawned and ready to buy Archangel's Staff.

there're sometimes Q & R didn't response too.