pfSense

That does not have issues with the first ip address but rather no strict linkage of vip/carp interface to its information.
That is what the patch i sent re-enforces.

Just FYI, I have a bridge interface with x.x.x.106 as primary IP, and an IP alias x.x.x.105. This fails consistently, ending up with .105 as the primary IP.

On which scenario and which version this happens?

2.1.5 and 2.2.0. After reboot the VIP becomes the primary IP, and all outbound traffic and firewall rules referencing 'bridge address' suddenly use the VIP instead of the interface IP, breaking things.

Can you share your interfaces config or all of it so i can replicate that?

Interfaces config, slightly censored: https://gist.github.com/MikeN123/009bc5fb76347663e448

Virtual IP config, slightly censored as well: https://gist.github.com/MikeN123/86fd05a7fb4b3c1f75de

Please let me know if you need any additional information.

Oh, and bridges and gateway config: https://gist.github.com/MikeN123/22d50fa3d37834b9659a

Same issue here, as stated in issue #5136.
Let me know if I can provide something useful.

This happens with bridges during boot because in interfaces_configure, interfaces_vips_configure is run before the interface_configure of the bridge interface, which leaves the IP alias first. There are a variety of catch 22s there with dynamic interface types (GRE, gif at least) because they may be dependent on VIPs, and the bridge may be dependent on them.

It works upon applying changes on interfaces.php because that uses interface_reconfigure rather than interface_configure, the process of which removes the IP aliases and adds them back so their order is correct.