DIAGNOSIS This is an HDMI-CEC (SIMPLINK) and device handshake failure. The TV is not properly detecting the active signal from the source on wake-up.
FIX First, enable HDMI Deep Color for that port. Go to Settings > All Settings > General > Devices > HDMI Settings > select the problematic HDMI port > enable 'HDMI Deep Color'. Second, disable Quick Start+. Go to Settings > General > turn off 'Quick Start+'. Power cycle the TV (unplug for 2 minutes). This forces a fresh HDMI handshake on each boot.
IF THAT DIDN'T WORK Manually set the input label. Go to Settings > General > Devices > HDMI Settings > edit the input label for that port to 'PC'. This changes the TV's video processing mode and can stabilize the handshake.
HEADS UP This model's HDMI ports can be sensitive to lower-quality cables. Use certified Premium High Speed HDMI cables. The issue is most common on HDMI ports 2 and 3. Try a different port as a diagnostic step.