Cannot mount external ntfs hard disk

[Snowhog]

He says he did.

I formatted two external hard disks (Western Digital 5To and HGST 1To) as ntfs using gparted.

[Bob Nelson]

Yes. Formatted with gparted.

[TinyTim]

2 times I had problems with ntfs, and 2 times, ntfsfix cured the problem. ntfsfix may already be installed in terminal, if not.
sudo apt install ntfs-3g -y
Then you point the command to the ntfs drive.
sudo ntfsfix /dev/sdX1 (sdX1 is a example, your drive should be found and entered in that place)
lsblk command will show you the drives.
As always, there are way more experienced users here than myself, I would wait for their input also.