A newly created section, if marked as hidden ("hide section from menu"), will be hidden in the backend from the association extension as well. Thus it is impossible create an association field and to connect it with the hidden section. One needs to unhide it first, then associate it and hide it again.
Wouldn't it be better to show all sections as possible associations in the backend, no matter what there visibility is?
A newly created section, if marked as hidden ("hide section from menu"), will be hidden in the backend from the association extension as well. Thus it is impossible create an association field and to connect it with the hidden section. One needs to unhide it first, then associate it and hide it again.
Wouldn't it be better to show all sections as possible associations in the backend, no matter what there visibility is?
From: https://github.com/symphonycms/symphony-2/issues/2658 cc @mprofitl