I’ve tested this and this is certainly due to some oddness in how librenms reads ISO (and other?) non-nfs mounts.
My environment is strictly linux based, but seeing as my issue and the other Windows environment ticket mentioned Mounting ISO image in Windows server causing incorrect disc space data enumeration have the same reporting oddities with the poller showing the mismatched/missing Storage INODE storage_index.
My current work around is remove the device and re-add via the lnms CLI. This is only temporary until another ISO/non-nfs mount is initiated on the device.