And yes, I did set the client cover art folder to the network server machine and verified the client can access the network folder/files.
Don't do that. At best it won't do anything. At worst it will break the Cover Art functionality. Okay, there may be some merit to it, but it isn't required. See Note 3.
My Client's Cover Art location in Options points to the local hard drive, in the default location, "C:\Users\[UserID]\AppData\Roaming\J River\Media Center 21\Cover Art\", as I don't keep any Cover Art on the Client. Cover Art works fine for my TV Series, Seasons, and Episodes art. Actually my Episode Cover Art is in the same directory as the recording, as I have MC set up that way.
Change your Client Cover Art location back to a local hard drive location, or a network location if you really want. (I wouldn't do that though.) But not the MC Server Cover Art directory.
When set up correctly the MC Server will serve Cover Art images to the Client, as required.
Take a look at the attached image. As you saved the JPG you created to the Cover Art directory yourself, rather than having MC save it, are you using the correct directory structure, as shown in my image?
All that you need is for a Series Cover Art JPG image file to be in the correct location, and the file to be named exactly the same as the Series name, in the case of Series Cover Art. That image file should be in the "\Cover Art\Series" directory. Season Cover Art should be in the "\Cover Art\Season" directory. TV Channel Logos should be in the "\Cover Art\Files" directory. Plus of course MC needs to know that the recording is from a TV Series.
-setting recording rule with tags for series matching name of jpg
I assume that the WTV files are not named so that CARNAC can identify the recording as a TV Series then, and read the Series name from the file name? Otherwise you shouldn't need to do that either. You may also need to set the [Media Type] to "Video" and the [Media Sub Type] to "TV Show" for MC to recognise the recording as a TV Show Series, and hence look for the Series Cover Art correctly.
Even though the "Get Movie & TV Info" function can't find Cover Art on TheTVDB, MC should find an existing Cover Art image when it imports the new recording. I say should though, as sometimes it can take a little while, and doesn't happen on import. Not sure why. Maybe it is the background Thumbnail process that finds the existing file. Or maybe it is just that Auto-Import hasn't run when I thought it had.
Note 1: All Cover Art maintenance must be done on the MC Server. If it is done on the Client, MC will save the Cover Art to the Client's Cover Art location, which will work on the Client, but it means that it won't be shared with the Server or other Clients.
Note 2: Sometimes Cover Art can get a bit screwed up, but usually there is a simple explanation. For example, I moved a whole bunch of video files a while back, but forgot to move their Cover Art. I didn't notice for a while, because MC was displaying Thumbnails of the Cover Art in the Theatre View views I was using. Then, progressively, Cover Art started to disappear, and were replaced by frame grabs from the video. What the??!! Simple: User error. I moved the Cover Art to where the videos now were, and did a "Quick Find In File / Cover Art Directory" and the Cover Art was all back. So, be careful moving stuff, and don't panic if Cover Art seems to go screwy.
Note 3: Using the MC Server's Cover Art directory on the MC Client may actually allow you to do Cover Art maintenance on the MC Client. But that would rely on all changes to Cover Art done on the Client being synchronised back to the server correctly. That is sometimes just a little bit unreliable. Also, if you made some changes, then closed the Client before the synchronisation happened, all the changes would be lost, even though the Cover Art image files were in the correct location. Not a disaster, as a "Quick Find In File / Cover Art Directory" on the MC Server should find the image and use it, but not ideal.
I would certainly advise getting Cover Art working on the Client first, and then test using the MC Server's networked Cover Art location.
Note 4: As CountryBumkin suggests, I think if you didn't delete each Episode as you watched it, before the next Episode is imported, then the Cover Art would appear immediately, since it is associated with an existing Series. Yet another reason not to delete episodes immediately.