It is possible to create a shared folders with a folder ID of “Comics.” Have noticed that if have ever used a folder ID previously a database sometimes gives some trouble when using it again. For example had a folder where the global file count was off. Tried removing folder and readding but the issue came back. Created a new share (with a new folder ID) and the issue was solved.
Are you sharing the folder (with folder ID “Comics”) from one machine and then clicking “add/ accept” or are you manually adding the folder ID “Comics” on both machines? Which ever way you are doing try the other way around.
Secondarily it may be easier to try again and use a random folder ID and just set the folder name to “Comics.”
An absolute sure way to make the folder ID “Comics” work is to delete the Syncthing database and re-add the folder you want to share with the folder ID of “Comics.” If you do this of course all Syncthing data will be lost so be careful with this.