Reverse RFC1918 local use zones unexpected behaviour

[Mehmed Kahric]

Hi,
I have 4 identical configured Unbound, and for 2 local configured stub for 10.in-addr.arpa subzone work as I expected, 2 not.
System is CentOS Linux release 7.4.1708 (Core) and Unbound 1.4.20 from base repo. Some details:

$ rpm -qa | grep unbound
unbound-1.4.20-34.el7.x86_64
unbound-libs-1.4.20-34.el7.x86_64

$ unbound-control status
version: 1.4.20
verbosity: 1
threads: 2
modules: 2 [ validator iterator ]
uptime: 961903 seconds
unbound (pid 7495) is running...

# /etc/unbound/unbound.conf
private-address: 10.0.0.0/8
local-zone: "2.10.in-addr.arpa." transparent
stub-zone:
  name: 2.10.in-addr.arpa
  stub-addr: 192.168.96.96
On first two Unbound query results is expected:

$ dig -x 10.2.40.50 @192.168.6.6

;  DiG 9.10.5  -x 10.2.40.50 @192.168.6.6
;; global options: +cmd
;; Got answer:
;; ->>HEADERHEADERHEADERHEADER
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