It sounds like the HDMI Control settings on your new RX-A4A may not be properly configured to allow for the desired behavior you're looking for.
First, make sure that the HDMI Control feature is turned on in the receiver's settings. This will enable the receiver to send signals to other devices over HDMI.
Next, check the HDMI Control settings for each device that is connected to your system. Make sure that the "Standby Through" or "Control for HDMI" feature is turned on for each device, which allows the receiver to control the power state of the connected devices.
If the issue still persists, try disabling any unnecessary HDMI Control features on your devices, as having too many settings enabled can sometimes cause conflicts.
Finally, if none of these solutions work, try resetting the HDMI Control settings on all of your devices to their default values, and then reconfigure them from scratch.
Hopefully, one of these steps will help you get the desired behavior from your system.