We had an instance of NCM that would only randomly download the configs of 27 nodes. Script execution was also affected.
Checking https://thwack.solarwinds.com/t5/NCM-Documents/NCM-few-nodes-failing-downloading-config-files-Connection/ta-p/532890 revealed that session tracing had been left on for several months from a previous troubleshooting effort. The folder had grown in immense size and must have hit a limit. Deleting all files and disabling session tracing rectified the issue.