Oops, I didn't know that WLM was updated, I'm still using WLM 2009 Build 14.0.8064.206 . I will update to Build 14.0.8089.726 and see if the issue is still around. Will post the results. Thanks.
(What are the release notes for this latest build?)
UPDATE: I updated to the latest WLM 2009 build but the bug is still present