I have a similar problem which was described before for earlier Illustrator versions - with the latest Illustrator 25.2.1 when one opens type>font> menu the arrow is not showing the list of fonts (is just a dead end) and ONLY that menu line is not working, I have to use Type window for choosing a font. I must say latest updates for Adobe are tragic - Photoshop after opening has to "think" and is not working for a few seconds - all of this is not a Windows problem and few Adobe updates back everything was working. We are paying for product which is going worse... WHY? I would prefer less often updates but optimized, tested and just working. Some people use your software for work.