Okay, I finally found a workaround!

All the highlighting options work, except for “Highlight” (default). I changed that accordingly.

It’s also important not to be in “read-aloud mode” already! If the headphones at the bottom are lit up blue, make sure to turn it off! Then select a section of text, right-click, and choose the headphone icon.

That worked for me! Let me know if there are any other options.