I tested on my standalone installation of MC, and it does indeed work correctly in that case, as it does directly on your server.
I then tested on a Client to my HTPC MC Server, and it always worked fine. The tag changed first time, every time, using your example "Beethoven: [HD 24/96] String Quartets, Complete (Emerson)" to replace the existing value for an Album tag.
I have 1450 tracks that include a "[]" pair in the Album tag, and 14 tracks in 3 Albums where the Album tag begins with a "[" and has a closing "]" in the tag. I can edit those and tagging all works.
I thought you are right about the "[]" Swiv3d, but now I think it is something to do with the installation. If tagging just didn't work at all on the Client I would suspect that Authentication wasn't set up correctly.
Bottom line, I can't repeat the problem. This is what I think is the problem:
I have 24.0.50 64-bit installed on my main computer, which controls multiple servers with a very large music collection. It is easier to make tagging changes on my desktop computer, which is CAT-5e networked with the main computer. I use the "sync" feature to make changes on the desktop library, then sync it with the library on the main computer.
From the Wiki:
Authentication
If your Library Server is available to the Internet (or if you are not sure if it is), use Authentication. In the server options, enable Authentication and set a user name and password that must be provided by the client before the connection is allowed.Also:
https://wiki.jriver.com/index.php/Library_Server_SyncI'm not an expert on how Authentication works, but it is also required to allow write access to the MC Server, and hence enable editing of tags. The actual UserID and Password for Read/Write access is stored on the MC Server, but the Client needs to provide that on first connection to the server, I think. It has been a while since I setup my environment.
If you are using one installation of MC to connect as a Client to multiple installations of MC Servers, Authentication may be getting "lost". You may need to close the MC Client (including any Media Server on the Client), restart the Client, and then connect to a different MC Server so that Authentication works.
I can't tell from the quoted post above exactly what your installation topology is. Do you have multiple MC Servers that you manage from one MC Client? If so, what is the "main computer"? It doesn't appear to be the same PC as your "Desktop computer"?
When you say you use the "sync" feature, do you mean the normal Client-Server synchronisation, or are you talking about the "File > Library > Sync Library..." function between your "Desktop computer" and the "main computer", which is completely different? To clarify, the normal Client-Server synchronisation function can be run from "File > Library > Sync Changes with Library Server", or by selecting the library under Playing Now and clicking the "Sync Changes with Library Server" button.
Please explain your environment and installation topology some more.