Many new fridges have a shutoff solenoid that prevents accidental overflows. Some leave the valve open for only 7 second on the ice tray. These can leave ice cubes half full or ice hollow.
Most ROs have a 1/4" line leading to the fridge, plus approximately 50' of line rolled up in the fridge. Pressure is lost. Also, there is a filter in the fridge. Take it out as it is not needed any longer since the RO produces greater quality of water. This may help.
You could increase the air pressure in the tank but that will give you less volume. There are 10 gallon tanks or add another tank to solve those problems.
Pulling some filters, they automatically go on a by pass. Others you may need to get a 'blank' cartridge.