I can't use the markup feature properly

Until yesterday, everything was working just fine in my Acrobat Reader, but today, by some reason I could not identify, the markup feature simply isn't working. If I open the tool, it shows the color that should be applied and everything, but when I try to use it it doesn't work. The same thing happens with the underline tool. It happens both when I try to mark or underline things with my Apple Pencil or handsfree.