Brizy breaks subscription box

Building my first website using WP/Page Builder Framework/Brizy (free). I've added a Posts subscription box to the sidebar on my posts page using a widget. I've tried with gopiplus and Email Subscibers and Newsletters and get the same problem with both. Abbreviated posts are showing OK on the Blog page but the Read More link (and the View option in the Post dashboard) opens the post in a blank page. If I disable Brizy the links open correctly, but all the other pages I've built with Brizy are garbled. If I reactivate Brizy and deactivate the subscription plugin everything works properly but the subscription box has gone (as expected).

Have I missed a simple setting to fix this, or is there a different subscription plugin that works with Brizy?