First, please let me say that I'm a just casual user of Mikrotik Routerboards and not a networking pro of any sort. Apologies if this turns out to be a silly mistake on my part.
ROS 6.33.5 on RB951Ui-2HnD
Executing a /system reset-configuration results in an unconfigured router. It seems that the "default-configuration" script fails to run or complete even though the "RouterOS Default Configuration" popup displays.
Fortunately the router is still accessible via MAC & Winbox.
The following screenshots indicates what happens.