Cisco Configuration Backup via Foglight NMS failing

Hi, I'm using Foglight NMS 6.0.20843 with a number of routers running Cisco IOS. Foglight is able to access the routers via SNMP (RO access), and is currently monitoring CPU and memory usage. However, it's unable to to backup their configurations. Configuration Backup in Settings -> Verify Monitoring Status always shows ERROR_FUNCTION_FAILED for all of the monitored devices. The devices are able to connect to the Foglight TFTP server manually (copy run tftp), and are able to successfully upload files, but I'm assuming the files are getting stored in the Foglight database rather than in the filesystem, as they don't appear in a search on the server. I confirmed that Foglight is listening on the TFTPd port on the server via TCPView. Does Foglight need read-write SNMP access to backup IOS devices' configurations? Is there logging occurring somewhere that might help troubleshoot, and/or more documentation than the "Cisco Config" page in the help file? Thanks!