CARP priority

[clarknova]

I have two pairs of OPNsense firewalls. All are running OPNsense 21.1.7_1 and both pairs are configured as CARP pairs with equivalent configuration, except the CARP master election appears inconsistent between the two pairs and I don't know why.

Pair 1:
router A CARP: 192.168.1.254/24 (vhid 1 , freq. 1 / 0)
router B CARP: 192.168.1.254/24 (vhid 1 , freq. 1 / 100)
CARP MASTER: router B

Pair 2:
router A CARP: 10.15.0.17/24 (vhid 1 , freq. 1 / 0)
router B CARP: 10.15.0.17/24 (vhid 1 , freq. 1 / 100)
CARP MASTER: router A

The election of CARP master is consistent. IE, if I reboot the CARP master in either pair, the backup router will promote to CARP master until the first router finishes booting, at which point the rebooted router resumes as master. Same if I disable CARP on the master then re-enable it.

The documentation indicates that the member with the lower Skew number is normally master. Why does my second pair follow this convention but the first pair does not?