"Not found on this server"

Hi! I want to make SOME of the posts on my blog available only to patrons. I use the Patreon Wordpress plugin, and on my posts I now get the “Sorry, this content is only for Patrons +++” and the button.

But when readers click the button, they get this message: “The requested URL/patreon-flow/ was not found on this server”.

I’ve come to understand that the cause may be that my permalinks are set to “custom”, and that I need to chose another.
The BIG problem is that if I do so, ALL my share counts disappear.

Is there any way to avoid this?

It depends on what kind of custom permalinks you are using though. If the patreon-flow like word based slugs arent working on your install, then the plugin cannot work.