Hello @jaap33
Hope all is well!
There is a JS error in the developer console which indicated a conflict with another plugin. Would you please deactivate all the plugins except Hustle and see if the opt-in will show up. If everything is well, activate one plugin at a time to find the one that causes this.
Just a note, in version 6.0 to show opt-in in a sidebar or with a shortcode please create and embed a form from Hustle > Embed and set a module to Live.
Hello @nicomollet
Looks like the Hustle opt-in is not active on your page, because I didn’t locate the plugin’s code. The Hustle should work with any cache plugin. Please see if the opt-in will be loading well when WP Rocket is deactivated; if all will be well please exclude Hustle’s JS files from WP Rocket Minification as it described in this thread
Let us know how it went!
Kind regards,
Nastia