Hyper-V cannot ping VM from host

Long story short: remove the virtual switch from Hyper-V, recreate it, and everything worked again...

reason is!!Firewall!!

Disable Firewall, or to be specific in the firewall settings, allow bellow app to communicate through fire wall and issue will be resolved:

File and Printer Sharing (ICMS)

Happened to me after host system update. VM client is Windows 7 and must have seen the updated virtual switch as a new network. Recreating virtual switch as above didn't work for me. Solution for me was to either

(1) within VM, set network location from Private to Home

-- or --

(2) within VM, allow network discovery in Private

Hope this helps.