BLACK SCREEN?
DO THIS.
1 — Remove everything unnecessary
Connect Source → Vertex → Display. One source. One output. No AVR. No second display.
↓
2 — Does Vertex show an RX signal?
No: troubleshoot source, source cable and EDID. Yes: the upstream side is alive; continue downstream.
↓
3 — Use a conservative EDID / source format
Use the Vertex Fixed EDID as a diagnostic baseline and/or lower the source to a simple supported format. The goal is first to obtain any stable picture.
↓
4 — Test Vertex directly into the display
Enable the display's correct Enhanced/UHD HDMI input mode. Try the other Vertex output and a known-good cable if necessary.
↓
5 — Picture works? Add HDR10
Only after SDR/basic video works, play known HDR10. Do not add Dolby Vision/LLDV yet.
↓
6 — Add devices one at a time
Add the AVR, then second display, then custom EDID/LLDV. The step that makes the picture disappear identifies where to investigate.