I know I asked this question a few years back or something similar, but I guess it didn’t stick in my brain. I’m trying to remember the expected behavior when it comes to saving tracks to favorites on a streaming playlist (Qobuz in my current example). So I’m in a Qobuz playlist playing through Roon Remote on my iPhone. Clicking the three dots menu on the now playing screen brings up “add to library” if it’s not already saved there. This I understand. But if a track is already in my library, that option is greyed out, logically. But it’s greyed out, it doesn’t show Remove from Library. And why is there no heart button option at the top? If I use Go to Album and look at the track, it’s the same, no heart button. Also missing in these situations is the Add to Tag option. I just get really confused by this. Somehow it’s not logical to my brain. So can someone explain the differences between being in a playlist, or maybe looking at my library tracks, or any other scenarios and what is possible and not?
I’m bumping my own question because I’m shocked no one has answered, even if it’s only to explain something obvious to me. 
The strange thing about Roon is, that an album from a streaming service that’s in your library, is regarded as another object than the same album not inside your library. Adding an album from a service to your library, is like making a duplicate of that same album.
When you are playing a playlist made by someone else, you actually play the object from outside of your library. This object cannot be removed from your library, because it’s not there. But you also cannot add it to your library, because the duplicate is there already.
This is a strange concept indeed, and I am sure Roon should or could find a way to overcome it, but it is what it is.
Ok, your answer makes sense even if the process doesn’t. What’s even more confusing about it is that Roon arc doesn’t behave the same. In arc, in a Qobuz playlist, I can add to library. Instantly, the add to tag and heart options appear. In arc, though, the remove from library option doesn’t show up for songs that are already in my library. I concur that this is really confusing.
It is. I suspect in ARC, the problem was solved partially.
I don’t recall seeing the very old thread before, I didn’t realize this was an old unresolved problem. But thanks, made for interesting reading.
@Victoria_Carlin the explanation is simple - it’s a bug. I have encountered the same behavior multiple times, but since I come from sotware development industry, I immediately saw it as a bug.
And there is also an easy way to verify this hypothesis - create smart playlist with a single rule that shows all the songs ‘added in the last day’. Now add any song to your library (e.g. from playing queue). The Add to library button will be disabled and no tags options will be available (as you described). But if you go to your smart playlist, you will have Remove from library and tags options available for your song.
So the problem in this case is that the user interface is not being updated after an action is made (adding song to library). And you can see this behavior all over the app. I recently wrote about similar data sync issue in this topic When does Roon refresh Smart Playlists? - #34 by Uros_Stanojevic
I find this behavior really frustrating, but what frustrates even more is that these issues are present for a long long time (in case of smart playlists for over a year). Some users in this forum like to suggest that an issue should be raised in corresponding topic (outside software discussions), but I am sure that the roon team is well aware of these issues, just don’t find them that important. But, sure, you can try reporting the issue. Good luck.