You wrote you already checked the "correct writing with SPI".
You should explainhow you exactly do that,- so as du000001 writes, at least you need to check both the clock and SDO pins when writing some byte like e.g. 0x33.
I see in the manual that SPI1 is not remappable, so no problems with PPS.
If your SDO and SCK is OK, and SDO is connected to SDI, then you possibly should show your SPI1_Exchange8bit function.
The purpose of OUT_11_ON is not clear, because you call it in the loop without setting anything OFF.
If something like this happens, and I think I have done everything correct, then I hard-wire SDI to Vcc. Your input should now be 0xff.
If not, check your wiring, I usually do this by just using SDI1 as a normal input pin (RA4 in your case, do not enable SPI). Does the input follow if you apply GND or Vcc to RA4 ?
If that works, then you can go back and check each and every setting of your SPI initialization code.
I did not take the time to verify comments against cryptic value.
It's usually better to use the definitions from the include file as you did it e.g. for