Issue
You are receiving Apps in this space use Automated Certificate Management which is not compatible with Trusted IP restrictions when attempting to add Trusted IP ranges to your Private Space.
You are recieving Trusted IPs are configured for this space. Automated Certificate Management is not compatible with Trusted IP restrictions when attempting to enable ACM for apps in your Private Space.
Resolution
Automated Certificate Management and Trusted IP ranges for Private Spaces are incompatible with each other. In order to add Trusted IP ranges to a Private Space that has apps using ACM, you will need to disable ACM for those apps (using heroku certs:auto:disable) and use your own SSL certificate (https://devcenter.heroku.com/articles/private-spaces#adding-custom-domains-and-ssl).
In order to enable ACM for apps inside a Private Space that currently has Trusted IP ranges, you must remove all the Trusted IP ranges (using heroku trusted-ips:remove) before proceeding to enable ACM for the apps inside the Private Space.
For further information, please see the known limitations for Automated Certificate Management: https://devcenter.heroku.com/articles/automated-certificate-management#known-limitations