Maybe something has gone askew in the upgrade. Have you tried to re-create the alert from scratch to see if that resolves the problem?
Sometimes task etc don't port over properly
hostname doesnt exist in 4.5 it would be detecting product hostname or target hostname
you may need to redo this in 4.5 with the new options
Duh@me of course hostname could refer top anything as you gave the result not the template but the names are different between epo 4 and 4.5 so you still probably need to recreate this
I had to re-create them anyway, they didn't come over in the upgrade.
This is what it was:
I changed it to:
I will wait and see what happens.
source is where it came from which is rarely populated anyway unless its a network worm, target/detected is what you want