I removed the other Wireguard client configs, and the issue persists. In Luci advanced config, the wireguard service is set to start, with priority 99. If I manually run this (/etc/init.d/wireguard start), then the VPN interface correctly comes up. So it seems that it’s not actually getting executed on startup.
Any ideas on what might be wrong? Any way to enable logging to get a better idea for why it’s not running? This is really frustrating because this router is setup at a remote location, and when the power goes out, there is no way to restore the VPN and someone has to physically go there and turn it back on.