When Microsoft updates your Cloud environment to Business Central 20.2, you must update the ForNAV app from AppSource. This is because Microsoft has, by mistake, disabled the event we are using for rendering. You can simply go to Microsoft AppSource and install ForNAV 22.214.171.124 or any later version.
The downside of this is that print to Excel no longer works.
Microsoft has promised to fix this problem with Business Central 20.3, which means you should expect to upgrade ForNAV again when Microsoft deploys BC 20.3