I've run into an issue recently that prevents me from casting Protection Field and a couple other powers on an Alert teammate if that person is currently targeting a hostile. Each time I target the teammate, when I cast the power, it immediately switches my target to the hostile. If that person is not targeting anything, I can cast it without issue.
It seems like it was treating the powers as attacks and autotargeting my target's target. I disabled "Assist target on attack" thinking it might help, but it didn't.
This only happens in Alerts. I can go into the Power House and find someone who is attacking training dummies, and it works fine, even if I'm teamed with them. But as soon as I try it on a teammate in an Alert, I'm no longer able to use the powers on anyone except myself.
Any ideas?
Update: This is happening sporadically now. It happens on multiple characters, but not in every Alert. No idea what's going on.