When I cleared two corrupted mosters from the tower event just minutes ago, but champions earned basic summoning bonds. Those summoning bonds were never received. I went immediatley to the items tab to use them, as I only have two champions at present, but they were not there.

Here is a screenshot of the victories that earned the summoning bonds:  https://prnt.sc/lgpbgd

Here is a screenshot showing that they were not received:  http://prntscr.com/lgpcq3

Lrod Jwhogrider

its not a bug. you got the bond in tower event and you have it on rewards screen

when the tower event will finish you will be able to claim all rewards including the bonds you got fighting against corrupted.

hope this can clarify ur doubts