We operate a 900+ WordPress Multisite install at http://europe-ecologie.net , and experiment Yoast SEO. In order to make it work on all sites, we network-activated it, and launched a batch that installed Yoast SEO options into all wp_XXX_options table. The aim is mainly to have sitemaps working on all existing sites. There's no error, except it seems necessary to go to the Yoast back end to save the Sitemap settings to get it working. If you do not do this, no sitemap is generated for the site (404 error). Once you do this, everything seems to run fine...
We use WP Super Cache.
Any idea ?