Did it occur to you that you have it not configured correctly? Probably wrong "Check ip method"...
I'm thinking in Namecheap Advanced DNS, I would remove the @ symbol for Host entry so your subdomains can individually update their IPs.
No no no, the pic make more sense without your "it's the wrong IP" because the IPs seem to be the same as updated and shown.So either the picture is right and you are wrong or the picture is wrong and you are right, but it's unclear what separates the first case from the second.You will have to make an effort for a reproducible bug report.
@Sakata_TUsing Namecheap myself and its working and updating all 4 of my Opnsense sites correctly within Opnsense AND Namecheap. Something is misconfigured or just different on your end with the Dual WAN. Cheers.Edited to note response was to @Sakata_T.
https://forum.opnsense.org/index.php?topic=34139.0