Diagnosis
This is a high-bandwidth HDMI handshake failure. The PS5 outputs a 4K120Hz signal by default, which exceeds the HDMI 2.0 bandwidth of the PX701-4K. The projector supports 4K60Hz maximum.
How to Fix It
On your PS5, manually set the HDMI output to a mode the projector can lock onto. Go to Settings > Screen and Video > Video Output. Set 'Resolution' to 2160p. Set 'Refresh Rate' to 60Hz. Disable '120Hz Output'. Set '4K Video Transfer Rate' to -1 or -2 to reduce bandwidth. This should create a stable signal.
If That Didn't Work
The HDMI cable is likely the issue. You need a certified High-Speed HDMI cable (18 Gbps minimum). Cheap or long cables often fail at 4K60. Replace the cable with a certified, high-quality one under 10 feet in length.
Heads Up
The projector's EDID (identity data) can sometimes get confused. A full power cycle can reset it: turn off the projector, unplug it from power for 2 minutes, then restart the signal chain (PS5 on first, then projector).