Fillable form stops being fillable

I have created a checklist for users to tick boxes when completing each action. The idea is that it can be completed from week to week from a mobile device, tablet or computer. There is no signature needed it is just a checklist with checkbox fields. After they complete the first time, the checkboxes have disappeared and cannot be ticked. (This happens on a mobile). How can this be rectified as the checklist is useless without the function of being to update it as they proceed through the month?