Dell Venue 11 7139 Pro wont boot from Win 10 flash drive

Hello,
I have a problem with Venue 7139 pro. Wont boot from flash drive with Win 10. No problem with Hirens USB or something else. Even when I plug in WIN10 USB drive and choose update BIOS (menu that shows if you press volume up during start up) I get a message unknown file system. BIOS version was A16, updated it to A21..but problem is still there. 

It doesnt matter did I choose UEFI or Legacy boot mode, the flash drive is not recognized at all. Secure boot is disabled, BIOS reset to default...

I tried 2 flash drives with Win10 and Venue doesnt recognize flash drive. I tried also the same flash drive in another Venues and it works...

So for I saw different issues with Venues, such as BIOS cant be updated (from A13 to A16), freezes during update, cant get into BIOS at all...but this is for the first time that Win10 wont boot from flash drive and that BIOS doesnt recognize flash drive at all!

Any idea?