Recently Google Chrome added password grouping that causes problems when you want to export all passwords at once. Here is a short tutorial how to turn off password grouping and enable export passwords button:
Open up Google Chrome on your computer, and type in chrome://flags in your address bar:
In search box type in grouping, then under Passwords grouping change Default to Disabled, and restart Chrome after that:
Open Google Chrome then go to Settings, Autofill and passwords, Password Manager:
That is it, Export Passwords button is back as it should be: