Are initial configs triggering some bug here?

As I get to Task 2.1 of lab 11 I find out R1's FR interface is up/down even though all
seems to be correctly configured:

R1
R1(config)#do sh run int s0/1/0 (I am not showing the subinterface but it has the initial configs applied)
Building configuration...

Current configuration : 71 bytes
!
interface Serial0/1/0
 no ip address
 encapsulation frame-relay
end

R1(config)#do sh ip int b | i Serial0/1/0
Serial0/1/0                unassigned      YES TFTP   up                    down 


R3
R3(config)#do sh run int s0/0
Building configuration...

Current configuration : 254 bytes
!
interface Serial0/0
 ip address 187.1.134.3 255.255.255.0
 ip pim sparse-mode
 encapsulation frame-relay
 ip ospf network point-to-multipoint
 ip ospf 1 area 134
 no fair-queue
 no frame-relay inverse-arp IP 302
 no frame-relay inverse-arp IP 305
end

R3(config)#do sh ip int b | i Serial0/0
Serial0/0                  187.1.134.3     YES manual up                    up 



I have worked labs 1-10 and I did not experience this issue before so just to test
I reset the interfaces and simply configured "encapsulation frame-relay" and now
both routers have up/up:


R1(config-if)#do sh run int s0/1/0
Building configuration...

Current configuration : 71 bytes
!
interface Serial0/1/0
 no ip address
 encapsulation frame-relay
end

R1(config-if)#do sh ip int b | i Serial0/1/0
Serial0/1/0                unassigned      YES TFTP   up                    up  



R3(config)#do sh run int s0/0
Building configuration...

Current configuration : 69 bytes
!
interface Serial0/0
 no ip address
 encapsulation frame-relay
end

R3(config)#do sh ip int b | i Serial0/0
Serial0/0                  unassigned      YES manual up                    up  






As soon as I configure an IP address on R1 it changes to up/down again...


R1(config-if)#do sh run int s0/1/0
Building configuration...

Current configuration : 71 bytes
!
interface Serial0/1/0
 ip address 187.1.134.1 255.255.255.0
 encapsulation frame-relay
end

R1(config-if)#do sh ip int b | i Serial0/1/0
Serial0/1/0                187.1.134.1      YES TFTP   up                    down
  

R3(config)#do sh run int s0/0
Building configuration...

Current configuration : 69 bytes
!
interface Serial0/0
 no ip address
 encapsulation frame-relay
end

R3(config)#do sh ip int b | i Serial0/0
Serial0/0                  unassigned      YES manual up                    up