Since the upgrade to 15.1.10 NTPd has been completely unstable. for some reason, it is unable to resolve the first server listed under Services > Network Time Protocol - whatever it may be (pool.ntp.org, north-america.pool.ntp.org, etc.), that is also only if stays running. most of the time, the process will crash with a core dump.
I have removed all settings, rebooted and verified BIOS clock is set to UTC. I have gotten it running, but I am afraid to do anything for fear of loosing ntpd again. I honestly have no idea how to provide you with information you could use. But wouldn't mind others reporting this issue or not.
for info, this is running the following: OPNsense 15.1.10-267d589a8 (i386)
any wouldn't you know it... now it's stable. I'm not sure what was happening. I wonder if my BIOS clock wandered too far away for NTPd to sync. But after 3 reboots, it's still holding up now.....