Revert system feature split-screen

I have official Android 9.0 ROM for HU PX5 GS rk3368. However, I think is more like general question. In my system, split-screen feature is disable (or just some apps are missing). I tried to set enable_freeform_support 1 but that did not helped. Note I did it by: adb settings put global enable_freeform_support 1 That is because Developer Options are also disabled (I can not enter - probably app / Activity removed) I'm pretty sure there is a way to fix that, but I don't have enough knowledge about Android to figure it out. I have access to root (over adb) **EDIT 1** After executing command and rebooting I checked if it was not reset to previous value settings get global enable_freefrom_support It returns 1 so it is ok. However feature is still not working. I also find out that following prop may disable spliting screen getprop ro.config.low_ram But it is not present in my configuration.