Wrong! Irregardless of your nationality, you shouldn't leave the vised me not to because I might not be let it. When there is a procedure underway to reach a decision (PR process in this case)that might affect your final status you mustn't exit. In the USA this is called adjustment of status n here implied status n same rules apply.
At the entry you must declare what is the purpose of your visit. It can b either TRS or PRS ie temp or perm status. If u show a trv I.e. a work permit in your case your purpose must b a temporary visit (until the permit is valid) not a permanent stay. If u have a wp n have initiated a permanent resident app that means you r entering the country with the wrong purpose I.e. the purpose of your intention (permanent) doesn't match the purpose of your entry ticket (temp stay I.e. wp). If u show the officer only work permit that means that the purpose of your stay MUST b temporary. U cannot show him a work permit (which is temporary until a certain date) and say that u intend to stay permanently. If u don't declare this u might become inadmissible due to misrepresentation. And if u do declare it, he might not let u back in because your document (wp in this case) doesn't authorize u to stay permananently unless u charm him/her