Good afternoon fesoyd1213,
I'm not aware of any strict code prohibition but I think it isn't a good idea if it can be avoided. If it's just they ordered materiel too short I'd say no splice and then sleep better at night. But if there is a compelling reason to splice I think it's possible.
While in theory you could develop capacity of the brace with CJP welds on HSS braces you'd lose a little of the total section capacity around the corners and on WF bracing you'd lose something at the weld access holes. If your brace needs to have ductility (SCBF) and you must splice due to some physical constraint, then you will want to position splices away for potential hinge regions (typically occurring at mid-span) and add cover plates over the splice region to gain back the lost net section area.
regards,
Michel