The available quantity is always 0 for users of type 'basic', even though the quantity is not 0 in admin.

[asok44]

[RBReif]

same problem here. Haven't found the cause yet.

[turboenator]

Demo website is same problem too, @amirsanni

[turboenator]

I may have found the cause, it's the superOnly() function in libraries/Genlib.php that prevents access if the user is not logged in or the role is not "Super" for Items.
If you want "available quantity" to work with "Basic" type users, you can temporarily disable the code:
$this->genlib->superOnly();
by adding // before
//$this->genlib->superOnly();
in controllers/Items.php (around line 18)
And find another way to prevent access if user is not logged in or role is not "Super" can Add New Item