Version 11.5.3 - Bug NTP server unreachable after upgrade

I recently noticed in couple of my ltm's, the NTP servers are unreachable after it got upgraded to 11.5.3. But I dont see any relevant article on this bug ID. Nor I observed any daemon log for this.

I was able to find another Q&A though.

[LTM:Active:In Sync] ~  ntpq -np
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
1.1.1.1   .XFAC.          16 u 20d 1024    0    0.000    0.000   0.000
2.2.2.2    .XFAC.          16 u 20d 1024    0    0.000    0.000   0.000
3.3.3.3.   .XFAC.          16 u 20d 1024    0    0.000    0.000   0.000

Hope this helps for others running on 11.5.3 to cross verify the ntp server status.

Resolution:

Restart the ntp service.

bigstart restart ntpd

If you can find an solution article, do share.