NOTE:
Use RPC to send coins if you get a warning using the send tab in the GUI...
EXAMPLE:
First fully unlock your testnet wallet.
sendtoaddress jMZfW9yKwbcujSpTWQnmUn3aJkhgg2Wix5 before and after the amount of coins>
I'm still unable to send tKORE to that address

Invalid KORE address (code -5)
Note: I'm still using v0.13.0.1
Since you were sent a single large block of coins if they staked then they need to mature.
Try closing wallet and put in conf file:
staking=0
restart and let a bunch of blocks go by for few hours and then restart and try to send.
Use the console to send them...
testnet wallet synced, is up and running
if you want to send some test coins please do , wallet going to be online 24/7
jNQQrLPdJ7ddjDY2svqUZg7gXVHyjSAxnD
sent 2,5k tKORE
I've already made another tx.
Just impossible to make any tx to the address you've posted.