Users with AMD frequently report the issue of under-utilization / low Space Coin production when first setting up the GFS app.
Here's what you need to do.
Set GPU to "compute"
You will see an up to 100% (!) increase in Space Coin production when switching the GPU workload settings to Compute.
Open the Radeon Settings and go to "Global Settings" and choose "Computer" in the GPU Workload dropdown.
Read this article by AMD to find out how to change your GPU settings to compute.
If you continue to experience your issue after following all the steps in this article, please create a Support Request to contact Support.