@wulfen
Tried your most up-to-date version of Daywalker. It echos in HB that it's casting spells, but the only spell I've seen it cast is Immolate and Corruption. I've watched the mob frame for DoTs, and I've watched for cast bars on my toon. The only cast bar that ever shows up is Immolate. I did see it cast Shadow Bolt one time through the entire time I was running it. It's still getting that "Invalid Target" error as well. It has a target selected, but I get spammed with "Invalid Target" until I either move it, or start combat with a completely different target.
I made sure that all the spells I have are used in the CC, and the spells I don't have are set to "Never" in the CC. It may also be that the options aren't saving? I noticed that whenever I set the "Drain Life" spell options, they never save and always revert to the default, which is blank.