i had this problem and if anyone still needs an answer. this is what i did that worked for me. i closed Ai. i left clicked the Ai tab in my taskbar then left clicked on Ai option from there i went to properties then Compatiblity tab on top clicked on that then change dpi settings then on the bottom an option override high dpi scaling behavior clicked on that and picked "application" from the drop down.
i had this problem and if anyone still needs an answer. this is what i did that worked for me. i closed Ai. i left clicked the Ai tab in my taskbar then left clicked on Ai option from there i went to properties then Compatiblity tab on top clicked on that then change dpi settings then on the bottom an option override high dpi scaling behavior clicked on that and picked "application" from the drop down.