I have noticed a similar bug when typing in the name of the owner I want to search in with the 'Find database objects' tool (and in other places too, like the parameter fields in test windows). Indeed I would end up typing 'YSS' instead of 'SYS'. The cursor seems to move to the beginning the moment you typed the second letter and then prints it there, making the first letter stay at the end no matter what else you type.