Unkillable Sentinels in DDQ

Uninspired

Playing the Big Enchilada in today's DDQ which includes several sentinels with Lokigator, Blob, and Ikaris. At some point I was unable to do any damage to the enemy (enemy health bars flashing every time) through matches or powers over several rounds, with and without charged tiles on the board. Note I had gotten three enemies downed (three left, Black Panther and 2 Sentinels) so could do damage for most of the match.

The Sentinels that negates damage upon matching multiple charged tiles was still in the fight with 21hp. So one explanation might be that the low hp and negation created an issue on activation. I also only fired Lokigator's yellow power near the end, and that may have had an impact? I did try playing again with the same team, not firing Lokigator's yellow, and had no issues.