I was having the exact same problem on my Macbook Pro.
Today I finally found the (easy) solution.
My Macbook has 4x USB-C ports, so to connect the USB-A plug I'm using a Hyper Slim USB C 8 In 1 Docking Station. My Apple USB Keyboard is connected to it (I'm using an external LCD monitor en keyboard with my laptop) as well as the USB cable that goes to the Arduino UNO.
I learned that the 5V one expects from the Hyper Docking Station is actually 5,03 Volt.
The problem of uploading sketches to my Arduino board was solved instantly when i connected the USB cable to the USB port of my Apple Keyboard. I measured the voltage of that output and found it was 4,96 Volt. Not a big difference one would think, but in my case it solved the problem of uploading sketches immediately!