Only on fbsd13 and only amdgpu: The EDID mechanism for reporting modes only for VGA interfaces is not getting modes from monitors. (AMDGPU) Other interfaces (HDMI DVI DP ETC...) work fine. The other kernel module components work fine (RADEONKMS AND THE INTEL)
Please provide some logs. If EDID read fails this should be log in /var/log/message
No news from original reporter, closing.