Still having this issue and found this
https://github.com/YunoHost-Apps/discourse_ynh/issues/16
which mention also the thing, I found now in my logs:
MaxMindDB (/var/www/discourse/vendor/data/GeoLite2-ASN.mmdb) could not be found: No such file or directory @ rb_sysopen - /var/www/discourse/vendor/data/GeoLite2-ASN.mmdb
The bad thing in this thread: No solution 