Execute ncurses programs not working, when skim input is a pipe

[perseas12]

OS: Linux Mint 19.3 Tricia x86_64
Base: Ubuntu 18.04 bionic
Kernel: 5.4.0-74-generic
Shell: bash 4.4.20
skim version: 0.9.4

Install an ncurses program like ncurses disk usage or nnn file manager:

sudo apt-get install ncdu nnn

Run the command:

find . | sk --bind "enter:execute(ncdu {})"

Select a directory and press Enter. The directory should open in ncdu, but nothing happens. Press Esc to exit skim. See the ncdu error:

Standard input is not a TTY.

Run the command:

find . | sk --bind "enter:execute(nnn {})"

Select a directory and press Enter. The directory should open in nnn, but nothing happens. Press Esc to exit skim. See the nnn error:

0 entries

The following commands work as expected:

sk --bind "enter:execute(ncdu {})"

sk --bind "enter:execute(nnn {})"