Maybe the app version is upgrading the driver.
Install 1.8.5 without installing the USB drivers and update the driver of the USB serial port with the updated drivers from FTDI D2XX Drivers - FTDI
Maybe the app version is upgrading the driver.
Install 1.8.5 without installing the USB drivers and update the driver of the USB serial port with the updated drivers from FTDI D2XX Drivers - FTDI