Fully agree @DavidC.........
For the record, the tank appears to be approx 1/4 full so I don't understand how either it developed an air lock or a temporarily block to the fuel supply. I also checked around the current fuel filter and it appears bone dry. From experience, any poor sealing(leaks) within the fuel supply leads to slow starting which I haven't been noticed.
On possible exception can be if it leaks on a high point.... and there is an air-pocket there.
I wonder if the tandem pump can be worn and "come and go" a little and make problems for you...
Look forward to hear what caused this..... every little problem solved is vital learning