Highlight problem

Hello, I have a Boox page When I open a PDF in Reflow mode (the text-based version that adjusts PDF text size to fit the device), and I highlight some text, the highlight doesn’t appear on the screen. However, when I check the content menu, the highlights are listed there. If I reset the PDF and exit Reflow mode, I can see the highlights. It seems the issue only occurs in Reflow mode. Is there any way to fix this problem?