Zero byte files

Since last week I have had problems with Calibre and transfering. All that I try to transfer to my Kindle Voyage show up as zero byte files in my Kindle in Calibre - and dont show up in my Kindle. When I check my Kindle as a drive - the files are there and can be opened normal.

I have just cheked with my wifes Kindle Paperwhite - same problem.

When I use "Send to Kindle" I can transfer the books witouth any problems except that Calibre says that there is two copies.....

I have used Calibre since Kindle dx witout any problems until now.......

I use win 10 and the newest Calibre.

Help please

Klaus Yde - Denmark