Strange NTP behavior on appliances running 2.6.1

I have a number of appliances (5220, 5230, 5330) - all of which are exhibiting strange NTP config behavior.  On all appliances I get the following when running a Network-NTPServer-Show:

<host>.Network> NTPServer Show
- [Error] Failed to add the following NTP servers: deninfrap6.jeppesen.com.
- [Error] Failed to add NTP servers from the appliance database.
<host>.Network>

Our NTP servers changed, so I only noticed this because I was trying to change to the new NTP servers.  I'm unable to do a "Add" of the new servers from the CLISH.  In addition, I'm unable to add them through the GUI.

I *was* able to elevate and simply modify the ntp.conf file and restart the ntp service.  So I'm good to go... but this issue seems strange and was hoping to see if anyone else has run into it?