Preview text selection in pdf doesn't highlight

Hi,

I'm trying to select a text in a pdf file opened with Preview but the tool won't show me what I'm selecting (won't highlight it). It is selecting because I can copy, use the highlight tools... I just can't see what I'm selecting and have to slide the pointer intuitively to select the text.

It started happening when I updated to Mojave 10.14 in my iMac 2017 (dark mode)

Thanks