ntpd disables "mode 7" queries by default due to security issues, consequently ntpdc doesn't work. ntpq still works because it uses mode 6 queries. (source: stackexchange). Since ntpdc is deprecated, we need to switch to ntpq.
vyos@vyos$ show ntp info localhost: timed out, nothing received ***Request timed out localhost: timed out, nothing received ***Request timed out
mode7 Enables processing of NTP mode 7 implementation-specific requests which are used by the deprecated ntpdc program. The default for this flag is disable. This flag is excluded from runtime configuration using ntpq. The ntpq program provides the same capabilities as ntpdc using standard mode 6 requests.