When setting static DHCP leases in Luci, I’ve noticed the leastime configured appears in /etc/config/dhcp, but does not get copied to /var/etc/dnsmasq.conf so it doesn’t get applied.
/etc/config/dhcp:
config host
option name 'Device name'
option mac 'xx:xx:xx:xx:xx:xx'
option ip '192.168.0.8'
option leasetime '43200'
/var/etc/dnsmasq.conf:
dhcp-host=xx:xx:xx:xx:xx:xx,192.168.0.8,Device name