Can't change the "Nextcloud data directory"

Hello, i’m trying to install nextcloud and use another dataset (not the default IxVolume) JUST for data storage.
i’ve noticed that during the installation of the app you are allowed to change the directory here:
So, i created a dataset and mounted it to the container:

This results in this confituration:
But when trying to deploy the container this happens:

I do not understand, i’ve experimented with the dataset’s permissions, and only allowing the “User - apps” but still the same error accours, why is this happening? do i need to set different permissions ?

Looks like you shouldn’t change the “Nextcloud data directory” directly
Instead, you shoud change where the data is stored from here “Nextcloud User Data Storage”:

And then, after creating a dataset, select it from the list as usual: