A while ago we re-installed our opmanager server on new hardware using the latest version to get a fresh start and clean databases. Since then I have 2 devices on my network with this same issue. Both are Sonicwall Firewall's model NSA 3500 (pre Dell). Both show no interfaces. I click discover interfaces and all the interfaces are correctly discovered. I tick the ones to add and click the save button, it reports 'interfaces added successfully' and it goes back to reporting "no interfaces are there for this device".

Previous to the rebuild we had these firewalls in opmanager showing all the statistics for the interfaces but now nothing.

So far I've tried a selection of fixes including rediscovering the device and deleting and re-adding the device, selecting different credentials and changing the vendor and device type.