rc15 stuck on first etcher client call to init USB drive partition table

If I run the etcher command from the command line (as administrator), same: it is stuck:

C:\Users\Kelson\AppData\Local\Temp\7zSC7CF.tmp\etcher-cli\etcher.exe -c -u -d \\.\PHYSICALDRIVE1
 C:\Users\Kelson\AppData\Local\Temp\7zSC7CF.tmp\mbr.img