I figured this is what the problem was. :) It's a great protection against spam and I don't mind it at all.
But I'm curious... tags still don't work too well for me. They work if I'm constantly watching a thread and look at every message like you suggested, but if I go away for a while and haven't read the recent messages and someone tagged me in one of those messages the tag doesn't show up. Is it supposed to be like that? I don't mind having to check the thread for my alerts to be fixed, but is there any way I can always be notified at least of my tags whether or not I check the thread? Those are sorta important. XD If I can't rely on the tags to give me alerts, there really isn't a point in them...
Someone tagged me about 2-3 times last night in a thread and I didn't see any of them on my alert list this morning. I actually searched through the thread and spotted them on my own... I could always search for them manually, but it really would be nice if I didn't have to. Tags aren't really spam because I actually want to see them, as do others. Some people aren't as diligent at checking threads as I am, and they have the same problem with tags, so if they don't see me tag them they never reply to my messages. I have to PM them or message them on Steam to tell them I replied in the roleplay. It's a bit of a hassle. XD And they always say the same thing: "Oh sorry! I didn't know you replied! It never showed you tagged me." So it would not only be helpful to those who want better alerts, but those who want to alert their friends too and actually feel comfortable knowing their friend DID get that alert.
Thanks for addressing this issue by the way! So many people talk about this all the time. XD If there's nothing that can be done about what I suggested, I understand. I just thought I would bring it to the attention of everyone here with that problem in case it is possible to do something about it in the future.