Some pixels' value becomes NAN after Terrain Correction

Hi everyone,
I intended to analyze the pol-matrix C2. I found some pixels’ values become NAN after Terrain Correction. These pixels are evident when zoom in .

I checked C2 without Terrain Correction. Pixels still had values.
Terrain correction was performed after C2 generated.
Is this caused by my fault?
I am very grateful for any hints!
thank you.

It probably treat 0.0 as NaN somewhere. Right click on the band name and select Properties. In the Properties menu, uncheck “No-Data Value Used” and change “No-Data Value” from NaN to 0.0. See if that helps.