Just to make sure we're speaking apple to apples not apples to oranges here.
Reports are for printing what is in the table.  Forms are what you would use to enter / change the data.

So...   If the item is checked in the table.  It will print as checked in the Report.

You can set a default in the form for a check box.  Did I miss something?

BTW - If there is an excess of 50 items to check off, I do NOT recommend having them in the same table.
You would actually want 3 tables.  CustomerT, JunctionT, and CheckItemT.  Then you would relate them using a Many-to-Many relationship.

This would allow you to delete or add items much easier in the future.

The checkboxes do NOT represent a field in the database. The report is really a "form" for a tech to check an item that will later be manually input into the database. Using a checkbox is simply a way of putting an item on the "form." Since checkboxes on a report, unlike checkboxes on a Access form, don't seem to have a property to preset the state. So, by default, the checkbox, when printed, is filled in with some fuzzy matrix of dots rather than empty. In order to make it clear, you have to set it to false. I did this in the OnLoad event to initialize. when you have 50+ of these, it's a chore to individually preset the state. In the old VB 6, you could create an array of checkboxes and the initialization woulf be a piece of cake. Access does not have this feature.

Use a For Each Loop to loop through all the Check Boxes on your report to set each one to False.

Dim ctrl As Control
    
For Each ctrl In Me.Controls
    If ctrl.ControlType = acCheckBox Then
        ctrl = False
    End If
Next

Thinking out side the box.
If this is just a way to print a report, what would be the drawback of setting up a dummy table - complete with the items you need - just for the report?   Then you could set the defaults to False and they wouldn't change.