LAN Topology features relies on LLDP data provided by switches.

You can check it right on the switch if hyou have enabled LLDP:

core-sw1# show lldp
  % LLDP is not enabled

# you can enable it like this
core-sw1# configure terminal
 Enter configuration commands, one per line.  End with CNTL/Z.
core-sw1(config)#lldp run

# check LLDP again
core-sw1# show lldp          
 Global LLDP Information:
    Status: ACTIVE
    LLDP advertisements are sent every 30 seconds
    LLDP hold time advertised is 120 seconds
    LLDP interface reinitialisation delay is 2 seconds

Or test LLDP values via SNMP from any host:

snmpwalk -v2c -c public <YOUR_DEVICE> 1.0.8802.1.1.2

Change community string from public to suit your needs. Does it display LLDP data?