Not sure what is wrong when you are doing, but it works fine on my lab:
[root@LABBIGIP2:Active:Disconnected] config # tmsh show sys connection cs-server-addr 172.20.0.101
Sys::Connections
172.20.0.10:52965 172.20.0.101:80 172.19.0.5:52965 172.19.0.6:80 tcp 0 (tmm: 3) none none
Total records returned: 1
[root@LABBIGIP2:Active:Disconnected] config # tmsh show sys connection | grep -F "172.20.0.101"
172.20.0.10:52965 172.20.0.101:80 172.19.0.5:52965 172.19.0.6:80 tcp 1 (tmm: 3) none none
[root@LABBIGIP2:Active:Disconnected] config #
cs = client side = connection side between the client and F5.
ss = server side = connection side between the F5 and server.
In my example:
cs-client-addr = 172.20.0.10
cs-server-addr = 172.20.0.101
ss-client-addr = 172.19.0.5
ss-server-addr = 172.19.0.6
Same idea applies if you are using the port instead of addr.