When calling host.create through api_jsonrpc.php with inventory object, inserting fails.
After investigation, error is the same as
ZBX-7561 : Field 'hardware_full' doesn't have a default value .
The source would be calling DBExecute directly from CHost::insert.
Not tested, but it seems that the example from the documentation ( https://www.zabbix.com/documentation/2.4/manual/api/reference/host/create ) wouldn't work.