AP Works Fine but cannot Ping Mikrotik

Hi,
I recently set up a Mikrotik as an AP with NAT. It has one ethernet and one wlan. I’m encountering a strange problem after NAT. I cannot Ping the Mikrotik PC from WAN interface but can perform traceroute successfully. During ping getting “Destination host unreachable”. But the Client devices connected to that AP works smoothly. What may be the problem?

Firewall