Found the problem. Monitor was connected to doc statin by DP cable and, at the same time, by USB cable After disconnecting USB everything started work properly  
I have a Latitude 7420 connected to a WD19TB dock which has one third-party monitor connected via DisplayPort.  After waking up from sleep mode PC doesn't turn on the monitor. If I connect the cable to the HDMI port to the PC and then remove - the monitor back from sleep. In any other cases, monitor doesn't wake up. BIOS Version/Date Dell Inc. 1.17.2, 15/06/2022 (latest) Intel Graphics driver 30.0.101.1692 (latest) HDR turned off on built-in display   [IMAGE]   Checked all topic on the Forum but didn't find the answer.
Latitude 7420 + WD19TB. Monitors doesn't come back on after sleep mode