Hi,
Here same problem. 5.26 version is perfect working. When I upgrade to 5.27.x versions there is an black screen without an input signal.
With hdmi_safe=1 I get the “loading image” after that the input signal is lost.
The config for 5.26 version with:sdtv_mode=2
sdtv_aspect=3
hdmi_group=2
hdmi_mode=85
disable_overscan=0
is working.