Loop DHCPDECLINE with Dnsmasq

Since some days I have infinite loop with dnsmasq DHCP… clients seems to refuse their IP that they were accustomed to having. We are talking about various clients, smartphones, PC, Mac,... I have only one DHCP server on my network. Only one subnet. Dnsmasq on 192.168.1.2, ISP router on 192.168.1.1

DHCPDISCOVER(eth0) d8:5d:e2:69:4b:77
DHCPOFFER(eth0) 192.168.1.192 d8:5d:e2:69:4b:77
not using configured address 192.168.1.73 because it was previously declined
DHCPDISCOVER(eth0) d8:5d:e2:69:4b:77
DHCPOFFER(eth0) 192.168.1.192 d8:5d:e2:69:4b:77
DHCPREQUEST(eth0) 192.168.1.192 d8:5d:e2:69:4b:77
DHCPACK(eth0) 192.168.1.192 d8:5d:e2:69:4b:77 Rdio-Salon
DHCPDECLINE(eth0) 192.168.1.192 d8:5d:e2:69:4b:77
not using configured address 192.168.1.73 because it was previously declined

My config:

no-poll
bogus-priv
domain-needed
stop-dns-rebind
cache-size=2048
expand-hosts
host-record=OdroidC2.b.net,OdroidC2,192.168.1.2
listen-address=192.168.1.2
log-async=25

dhcp-range=192.168.1.150,192.168.1.250,12h
dhcp-option=option:router,192.168.1.1
dhcp-option=6,192.168.1.1
dhcp-leasefile=/var/dnsmasq.leases

Please help. How do I investigate? Why do customers decline their IP?

Thank you very much !!!