The part of the bootloader that handles deep sleep is a closed source blob that Amlogic provides. Ugoos would have to get Amlogic to provide them with a fix.
The default suspend option in CE is suspend-to-ram, the am6+'s IR receiver probably isn’t working in this state from CE. You could use suspend-to-idle which is the step right before suspend-to-ram. That turns off a bunch of the boards functions, and puts 5 of the 6 CPU cores offline. The IR receiver is still functional at this stage for waking.
I made a script for the 2nd gen Cube to use suspend-to-sleep that would probably work with the am6+ with a couple tweaks.