There are three branches and the central office:
Branches normally Ping headquarters and not ping each other
Thank you, I will tryYou are most likely hitting the split horizon limitation of RIP. I don't believe that MikroTik has the capability to disable split horizon like you can in Cisco.
The options you can consider are:
1. Move to OSPF - it is a far better and faster routing protocol than RIP
2. Enable a full mesh of tunnels between sites
3. Add static routes to make up for the routes being stopped by split horizon.
I would strongly recommend option 1 to make routing easier.