Export to PDF glitch

I am using a macbookpro (Apple chip) OS 11.4 and SU LayOut 2021.

This problem has gone on for a long time and is not related to the Apple M1 chip. It also occurred when I was using an Intel chip macbook pro.

I have a LayOut document that uses a graphic of a white brushstroke on a clear background set in front of a black band. The image is a Photoshop file (.psd) It appears correctly in LayOut, and it appears correctly if I choose Print > Save as PDF. But if I export the file from LayOut as a PDF, the whole thing turns white.

Why does Print > Save as PDF work when Export does not?