Sometimes you have to wait some minutes to get NTP server synchronized. Might be up to 10 or 15 min.
Check with show ntp asso detail for more information.
Sometimes it is useful to enable: debug ntp all and read the logs. It is just a few lines per m...
I have observed a similar case with C9300 switch.
Here the remedy was to remove the ntp trusted-key <key> and configure again. After that the switch had exchanged the key with NTP server successfully.
ip access-list resequence 100 10 10 # with 100 = access-list number ; 10 = first number in access-list and 10 steps for increment the next number in the access-list
