Actually I had the same problem, and it may take more then transferring your DNS name server to Digital Ocean and add the domain, then wildcard domain and expect just to work.
Let me explain what I’ve found out so far.
Digital Ocean APP platform uses CloudFlare and proxies the request throughout them, which is great as it adds extra security layer and DDOS protection, but when it comes to wildcard domain setting CNAME record is simply not enough. ColudFlare can fail proxy your wildcard domains, and you may end up with Error 1016 Origin DNS Error, even though your wildcard SSL certificate is valid.
It requires you to make additional changes in your DNS records. CloudFlare can only pass your wildcard subdomain if you are using “CNAME Flattening” (sometimes called an alias record, or ANAME). If you have the above error, please learn about CNAME Flattening.
I am happy that it was resolved on your side, but if someone else have the same problem, this might help.