I guess we need to start with the obvious questions! Are all the components up to date? And – are you installing the subscriptions SP plugin in the right place? (I.e, by default wp-content/sp-resources/forum-plugins/subscriptions/… etc)?

And if yes to those answers perhaps you could take a look at the forum admin > toolbox > error log and tell me if there are any listed as an actual error (i.e., shaded pink) and if so paste the text here

Sorry. All updated and all working now. Thank you

Great news. Thanks for the update