This usualy happens at the end of season and they are still trying to fix the game
When this happens the best thing to do is play the game using the mobile version the game still works for some reason in your phone unless it is maintainance time and all you can do is wait
Tip: When the season is about to end try to spend your energy capture rate to at least 80% meaning you are leaving 20hrs of recovery time for it or maybe more depending on your gaming habbits but usualy because of overload problems after the season you may not be able to play and the energy will be wasted
Thanks for reading till next time remmember planning ahead is always a good thing ^^