Post indexer won't index my Multisite


I've installed the Post indexer plugin (sitewide activated) on my multisite (4.6.1). I plan to use it in combination with the Live stream widget to show on my main site:

1. Products from a specific subsite on a subdomain which has Woocommerce installed

2. Posts from all other subsites which are created by my users/clients.

But after two days, indexing. Nothing shows up in the statistics, even when i manually rebuild the index (and wait for a couple hours). Also, the livestream widget shows no content.

Another strange problem is that i can't select the "product" post type in the sites view network admin, when i click on "edit" next to the specific woocommerce subsite. It won't save my settings. Even when i fill in "product" on the global settings -> default post type field.

There are no errors in the browser console and i can't discover related php errors.

Thanks in advance!