Just want to say that I also have this issue on 2.4.4. I've checked the logs to find this
Nov 13 09:43:51 dhcrelay Disabling output on BPF/vmx1.2202/00:50:56:94:4b:66
Nov 13 09:43:51 dhcrelay Disabling input on BPF/vmx1.2202/00:50:56:94:4b:66
Nov 13 09:43:51 dhcrelay receive_packet failed on vmx1.2202: Device not configured
repeated for each interface setup for DHCP Relay. Restarting the service fixes it, but I'd rather not take mcarson75's solution of setting up a cron job to fix this.