[GAMEPLAY] Can't use Devour ( Tahm Kench '' W '' ) on my ally ADC ( caitlyn )

During a game, me and my friend was duo bot Caitlyn and Tahm Kench during a normal game, In mid game, I get DC from pvp.net for unknown reason for 2 minutes ( curse , net still working fine ) . When I come back, my friend also DC ... strange ? At this moment , I couldn't no longer used my skill Devour on him but other teammates yes ( and I tried many times ). I died , and the bug still there.

Not my first game with TK , but first time happened. I dunno if is a new TK bug , but here my bug feedback ! Thanks !