Ok, now check if it created the snmpwalk in ~/var/check_mk/snmpwalks/HOST.
If the file is present, go to “WATO -> Access to agents -> SNMP: Simulating SNMP by using a stored SNMP walk” and set this rule for the HOST you previously stored the snmpwalk for.
After applying the rule, run the inventory for the host again and see if it finds the services. Enable the services you want to monitor. Apply the changes so the core restarts and the config files get written. After that you can delete/disable the rule for simulated snmpwalk and see if the host and its services get checked correctly without any timouts.