Destination port is missing from dnstap captures of client traffic

With the following configuration:

options {
	listen-on port 5300 { 127.0.0.1; };
	listen-on-v6 port 5300 { ::1; };
	dnstap { client; };
	dnstap-output file "dnstap.log";
};

named produces the following dnstap data:

$ dnstap-read dnstap.log 
27-Apr-2022 13:25:53.672 CQ ::1:36670 -> ::1:0 UDP 48b isc.org/IN/A
27-Apr-2022 13:25:53.675 CQ 127.0.0.1:53203 -> 127.0.0.1:0 UDP 48b isc.org/IN/A
27-Apr-2022 13:25:53.998 CR ::1:36670 <- ::1:0 UDP 80b isc.org/IN/A
27-Apr-2022 13:25:53.998 CR 127.0.0.1:53203 <- 127.0.0.1:0 UDP 80b isc.org/IN/A

Note the ::1:0 and 127.0.0.1:0. The proper, expected data is:

$ dnstap-read dnstap.log 
27-Apr-2022 13:27:04.725 CQ ::1:58931 -> ::1:5300 UDP 48b isc.org/IN/A
27-Apr-2022 13:27:04.725 CQ 127.0.0.1:44892 -> 127.0.0.1:5300 UDP 48b isc.org/IN/A
27-Apr-2022 13:27:05.215 CR ::1:58931 <- ::1:5300 UDP 80b isc.org/IN/A
27-Apr-2022 13:27:05.215 CR 127.0.0.1:44892 <- 127.0.0.1:5300 UDP 80b isc.org/IN/A