Hmm, I tested it this morning and it appears to be working fine. Could it be that you entered a name less that 4 characters? There is a 4 character minimum on names. I'll be sure to add an error check on the names for length.
EDIT: After looking at the code I discovered the fix I put in to test Planet names for 4 characters also applies to fleets. So yes there is a fix in the current build.