Did you ensure that LLDP is enabled and running correctly on those switches? have you configured SNMP traps? Oneview pulls information from the LLDP MIB tables and from LLDP traps. You are probably getting the link from the Extreme switch because we get the information from that and can draw one link, but since the other devices either are not sending/do not have the right MIBs, we cannot pull that information and draw additional links.