Junos OS: Firewall filter terms named "internal-1" and "internal-2" being ignored

When configuring a stateless firewall filter in Junos OS, terms named using the format "internal-n" (e.g. "internal-1", "internal-2", etc.) are silently ignored. No warning is issued during configuration, and the config is committed without error, but the filter criteria will match all packets leading to unexpected results. Affected releases are Juniper Networks Junos OS: All versions prior to and including 12.3; 14.1X53 versions prior to 14.1X53-D130, 14.1X53-D49; 15.1 versions prior to 15.1F6-S12, 15.1R7-S4; 15.1X49 versions prior to 15.1X49-D161, 15.1X49-D170; 15.1X53 versions prior to 15.1X53-D236, 15.1X53-D496, 15.1X53-D69; 16.1 versions prior to 16.1R7-S4, 16.1R7-S5; 16.2 versions prior to 16.2R2-S9; 17.1 versions prior to 17.1R3; 17.2 versions prior to 17.2R1-S8, 17.2R3-S1; 17.3 versions prior to 17.3R3-S4; 17.4 versions prior to 17.4R1-S7, 17.4R2-S3; 18.1 versions prior to 18.1R2-S4, 18.1R3-S4; 18.2 versions prior to 18.2R1-S5, 18.2R2-S1; 18.2X75 versions prior to 18.2X75-D40; 18.3 versions prior to 18.3R1-S3; 18.4 versions prior to 18.4R1-S1, 18.4R1-S2.