Hallo Jacob,

the error message comes from pflogd(8) here (sbin/pflogd/pflogd.c):

    557 /* append packet to the buffer, flushing if necessary */
    558 void
    559 dump_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
    560 {
    561         FILE *f = (FILE *)user;
    562         size_t len = sizeof(*h) + h->caplen;
    563
    564         if (len < sizeof(*h) || h->caplen > (size_t)cur_snaplen) {
    565                 logmsg(LOG_NOTICE, "invalid size %zu (%d/%d), packet dropped",
    566                        len, cur_snaplen, snaplen);
    567                 packets_dropped++;
    568                 return;
    569         }

> Jul?? 2 14:35:33 mystic pflogd[77507]: invalid size 180 (160/256), packet
> dropped
> 

    the '(160/256)' in log indicates the pflogd's snaplen must be increased
    from 160 (default) to 256 bytes. According to pflogd(8) manpage you need
    to start your pflogd process as follows:

	pflogd -s 256

if you run daemon by rc scripts at boot time you need to run command:

    rcctl set pflogd flags '-s 256'
    rcctl reload pflogd

this should get you going.

good luck
and regards
sashan