Why does iPad Pro create files on USB devices?

[iKevinJ]

I have a new iPad Pro 12.9”, using a couple different USB devices for photos and videos. USB thumbdrive and USB external SSD hard drive. Every time I view the files stored on the external storage devices, the iPad creates files onto the external device with same name but beginning with a period, and always 4MB in size. Many times when plugging the device into my PC’s afterward, the PC says the device needs to be repaired. IPad and PC’s (2 of them) running latest iOS and Windows10.