yep, caching. writing to flash memory used to be painfully slow. this issue has existed with windows since usb storage was invented. early on, windows wouldnt even assign a drive letter correctly (a winworld requirement).. you had to do it manually. so painful.
No , you can't write it as you don't have it mounted. You did ? Well it's not accessible through specific programs (like may be Plex or unusable word like software that saves format file in format unknown to 90% of world) forget about it.