The latest plugin update is not working on 6.12.8. I'm seeing this in the syslog:
Apr 3 23:50:27 hp root: plugin: skipping: nut-2.8.1-x86_64-5master.ssl31.txz - Unraid version too low, requires at least version 6.13
Apr 3 23:50:27 hp root: plugin: skipping: nut-2.8.2-x86_64-1stable.ssl31.txz - Unraid version too low, requires at least version 6.13
Apr 3 23:50:27 hp root: plugin: skipping: nut-2.8.1-x86_64-3stable.ssl31.txz - Unraid version too low, requires at least version 6.13
Apr 3 23:50:27 hp root: plugin: skipping: nut-2.8.0-x86_64-3stable.ssl31.txz - Unraid version too low, requires at least version 6.13
Apr 3 23:50:27 hp root: plugin: skipping: nut-2.7.4.20200318-x86_64-1.txz - Unraid version too low, requires at least version 6.13
Apr 3 23:50:27 hp root: plugin: skipping: - Unraid version too low, requires at least version 6.13