Your lawyer is incorrect. If you still have a valid WP you can leave and reenter the country. There is always a small chance you can refused entry everytime you leave Canada if you aren’t a PR or citizen, The issue is if you try to leave after your WP has expired and when you’ve applied for an extension so during the time you are on implied status. At that point you won’t be able to reenter. Are you currently working? Will you be working when you leave Canada and try to reenter?
Change lawyers.