try all DTBS for rk3328 from the image
Masking mode can only be used if the regular loader is blocked from any steps to launch from external media (SD card). In other cases, this is a bad decision. Specifically for the A5X, there is no blocking and for proper operation, you only need to select a dtb for the u-boot build with a full launch without any masking mode. This is easy to do if you have a sample device.