for those facing the same situation, I have a workaround. While waiting for a solution (I looked at the code on github, and know that I won’t be able to fix the thing), I am using a redirection plugin to redirect the wrong url to the correct one. Code 301 is still better than code 404. Hope that it helps.
More info: this issue happens not only on the author page but also on product category page where I customized the slug. I guess if one could change those slugs in the msls settings, that would solve the problem.
Thank you for your reply. I think that removing plugin folder solved the problem.
