DHCP strange issue

After update from 4.14 to 4.15 and 4.16
dhcp server make a strange problem with some hosts (vivotek ip cameras)

log dhcp debug

10:34:54 dhcp,debug,packet PrivateLanDHCP received discover with id 1415040068 from 0.0.0.0 
10:34:54 dhcp,debug,packet     ciaddr = 0.0.0.0 
10:34:54 dhcp,debug,packet     chaddr = 00:02:D1:0D:23:37 
10:34:54 dhcp,debug,packet     Msg-Type = discover 
10:34:54 dhcp,debug,packet     Client-Id = 01-00-02-D1-0D-23-37 
10:34:54 dhcp,debug,packet     Class-Id = "udhcp 1.12.4" 
10:34:54 dhcp,debug,packet     Unknown(57) = 02-40 
10:34:54 dhcp,debug,packet     Parameter-List = Subnet-Mask,Router,Domain-Server,Host-Name,Domain-Name,Unknown(28),NTP-Server,NETBIOS-Name-Server

this make pool filing with strange leases

Flags: X - disabled, R - radius, D - dynamic, B - blocked 
 #   ADDRESS                  MAC-ADDRESS       HOS... SERVER    RAT... STATUS
44 D 172.16.0.2                                        Private          busy   
45 D 172.16.0.3                                        Private          busy   
46 D 172.16.0.4                                        Private          busy   
47 D 172.16.0.5                                        Private          busy   
48 D 172.16.0.6                                        Private          busy   
49 D 172.16.0.7                                        Private          busy   
50 D 172.16.0.8                                        Private          busy   
51 D 172.16.0.9                                        Private          busy   
52 D 172.16.0.10                                       Private          busy   
53 D 172.16.0.11                                       Private          busy   
54 D 172.16.0.12                                       Private          busy   
55 D 172.16.0.13                                       Private          busy   
56 D 172.16.0.14                                       Private          busy   
57 D 172.16.0.15                                       Private          busy   
58 D 172.16.0.16                                       Private          busy   
59 D 172.16.0.17                                       Private          busy   
60 D 172.16.0.18                                       Private          busy   
61 D 172.16.0.19                                       Private          busy   
62 D 172.16.0.20                                       Private          busy   
63 D 172.16.0.21                                       Private          busy   
64 D 172.16.0.22                                       Private          busy   
65 D 172.16.0.23                                       Private          busy   
66 D 172.16.0.24                                       Private          busy

no mac addresses as you see.

Any suggestions?