Fortigate CLI execute ping-option source cant use ip pool

Probably that's not the FGT issue, but ISP is not responding what ever the reason.
Have two CLI sessions into the FGT, then at one of them run a sniffing like

    diag sniffer packet any 'icmp' 4 0 l

Then at the other one, run like

   exe ping 1.1.1.1

after setting the source to 1.1.1.2, .3, or .4. In the sniffing, you would see the ping packets are going out through wan interface, but nothing is coming back from the ISP.

Toshi