After digging manually through the configuration classes I was able to find and add the following, which did the trick…
security.oauth2.client.pre-established-redirect-uri=https://[application_host]/login
security.oauth2.client.registered-redirect-uri=https://[application_host]/login
security.oauth2.client.use-current-uri=false
I’m not convinced there isn’t a better way to solve the problem of forcing a HTTPS redirect URL, but this fix worked for me.