QSPI read fail.

Hi Sir 

I try to write/read/earse any address with length 32. 

but some bytes shows zero "0x0" when I use , it should be 0xff after erasing...

Do you know what's the problem ? Thanks.

[00:00:30.151,791] <info> app: 0xFF
[00:00:30.151,798] <info> app: 0x0  //??
[00:00:30.151,804] <info> app: 0x0  //??
[00:00:30.151,810] <info> app: 0xFF
[00:00:30.151,816] <info> app: 0xFF
[00:00:30.151,822] <info> app: 0xFF
[00:00:30.151,829] <info> app: 0xFF
[00:00:30.151,835] <info> app: 0xFF
[00:00:30.151,841] <info> app: 0xFF
[00:00:30.151,847] <info> app: 0xFF
[00:00:30.151,856] <info> app: 0xFF
[00:00:30.151,862] <info> app: 0xFF
[00:00:30.151,868] <info> app: 0xFF
[00:00:30.151,874] <info> app: 0xFF
[00:00:30.151,881] <info> app: 0xFF
[00:00:30.151,887] <info> app: 0xFF
[00:00:30.151,893] <info> app: 0xFF
[00:00:30.151,899] <info> app:

[00:00:30.151,905] <info> app: 0xFF
[00:00:30.151,911] <info> app: 0xFF
[00:00:30.151,918] <info> app: 0xFF
[00:00:30.151,924] <info> app: 0xFF
[00:00:30.151,930] <info> app: 0xFF
[00:00:30.151,936] <info> app: 0xFF
[00:00:30.151,943] <info> app: 0xFF
[00:00:30.151,949] <info> app: 0xFF
[00:00:30.151,955] <info> app: 0xFF
[00:00:30.151,961] <info> app: 0xFF
[00:00:30.151,967] <info> app: 0xFF
[00:00:30.151,974] <info> app: 0xFF
[00:00:30.151,980] <info> app: 0x0  //?
[00:00:30.151,986] <info> app: 0x0  //? 
[00:00:30.151,992] <info> app: 0x0  //?