Boox Page Neoreader highlight issues

Recently got my Page and enjoying it so far. However, when I try to highlight some sentences in Pdf files (with zotero), they disappear. It’s like some words ‘cant be highlighted’ and I have to work around it by only highlighting the first word of the sentence.

I select a sentence to highlight, I let go (auto highlight is on), it shortly blinks black and it disappears. Any ways to deal with this? Is this an issue in the reader, file, or zotero?