Could you please have try with the latest mainline kernel: https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.3/
If that kernel doesn't work, let us have a try with replacing the current graphic driver amdgpu to the amdgpu-pro.
I will update a new comment to explain how to install amdgpu-pro if the kernel v5.3 is confirmed to not work.
Could you please have try with the latest mainline kernel: https:/ /kernel. ubuntu. com/~kernel- ppa/mainline/ v5.3/
If that kernel doesn't work, let us have a try with replacing the current graphic driver amdgpu to the amdgpu-pro.
I will update a new comment to explain how to install amdgpu-pro if the kernel v5.3 is confirmed to not work.