Carnac runs on Auto-Import. Files that are not imported are not processed.
You can't use the Drives & Devices item to test it, unless the files are imported.
Mine works fine.
My new imports list processes all the files Sage records properly, removes the junk numbers at the end, inserts spaces as appropriate (95% of the time, a few things do slip through, but it is pretty darn good), and the Auto-Lookup works correctly in most cases without massaging the metadata manually.
I can post a screenshot if you don't believe me, but my New Imports view is full of recordings that are all properly tagged, with cloud metadata, and everything. It doesn't work for every single file (usually if the [Series] tag Carnac pulls from the Sage filename doesn't match the Series name in thetvdb.com, or the Movie name isn't "quite right"), but the percent where it works is very high.
I disabled most of my Sage plugins when I switched to using MC. I have just the Webserver and some basic UI functionality plugins enabled now. I have
nothing in Sage that is metadata related enabled. (Incidentally, Sage seems much more reliable now.)
FWIW, I added the functionality to DTB as an action so every time something records the sidecar file is written. I use that approach instead of letting MC figure it out primary because it accounts for recording padding, so I don't have to watch that if I don't need to.
To Be Clear: This functionality would "break" Carnac if it is enabled, and you would get basically exactly what you are seeing.
Testing it should be simple:
1. Close MC (even the Server) completely.
2. Record something in Sage.
3. Look at the recording on disk (be sure to give it a little while after the recording finishes). If there is a JRSidecar.xml file there, then something other than MC is writing them.
If there is a JRSidecar file there, then MC will use the data in the file when it imports it, and Carnac doesn't process those fields. You can easily open up the JRSidecar file in a text editor to see what it contains.