Not quite sure what you mean by this question. However if you are trying to connect to a gateway with ssh and a user that defaults to clish, or when you are able to login with a bash user and from there you try to go to the clish prompt and in both cases it just sits there and not much is happening, at least so it seams. Then I must say yes, had one of those cases last week on a system that was running for 480 days or so.
When you have this problem, yes the only way to resolve is to reboot.
Regards, Maarten