@Fawaz-Kalathingal, I hope all is well. So some general background that might be helpful here:
The XMAS (inverse), FIN & NULL scan types are exactly the same in behavior except for the TCP flags set in probe packets.
If a RST packet is received, the port is considered closed, while no response means it is open|filtered.
The port is marked filtered if an ICMP unreachable error (type 3, code 0, 1, 2, 3, 9, 10, or 13) is received.
The big downside with these scans is that not all systems follow RFC 793 to the letter. A number of systems send RST responses to the probes regardless of whether the port is open or not.
This causes all of the ports to be labeled closed.
Another downside of these scans is that they cannot distinguish open ports from certain filtered ones, leaving you with the response open|filtered.
So, it is very likely that you have open ports but are not able to correctly identify them due to the limitations of the tool.
Have you tried other scans to cross reference and verify the state of the systems being scanned?
Have you locally verified, where you can, that ports are open on one or more of those systems using a different tool/command set?
It is a game of inches, and you have to be prepared to move backwards to advance form a different direction to fins success.