First of all - thanks for building this plugin! It's incredibly useful and I appreciate your contribution to the WP community.
I recently upgraded Yoast SEO and it seems to have reintroduced a conflict with PPP. Your FAQ states:
Q: I have activated the "WordPress SEO by Yoast" plugin and enabled the option "Redirect ugly URL's to clean permalinks.". The public preview doesn't work. What can I do?
A: Please add _ppp to the input field "Other variables not to clean:" on SEO -> Permalinks screen.
In the new Yoast, there is no such field in the Permalinks screen. Could you let me know how to fix this problem (and update the FAQ as well!).