NMAP shows Filters on Server own IP

I came to realize that something weird was happening on my server. When I run nmap --reason <server's own IP>, all services were filtered with reason as no-response. But the same was not the case if I run nmap on another server towards this server. On this server, nmap 127.0.0.1 didn't show this problem too.
But I couldn't figure out why and what was filtering the server's own ip. Did anyone see this kind of behavior?