I've had the same problem in a Document Template and solved it by adding this to the custom style of the template grid's main table:
break-after: page;
If your Template Grid is at bottom of your Document Template and you don't want to generate an empty last page you can also use:
break-before: page;
If you just want a line break, you can probably trick this by using static labels containing a space.
Because a template grid is placed on a form and not on a document template. You set the amount of rows in the template grid properties to achieve something like a page break. In a templategrid you can add extra cells below your object, to insert a line-break. Are you confused with the document template?
Edit after comment with example:
start of table [row][cell] Header with some info [/cell][/row]
[row][cell] attribute of object[/cell][/row]
[row][cell] Templategrid with associated orders[/cell][/row]
[row][cell] Pagebreak[/cell][/row]
[row][cell] Templategrid with associated other objects[/cell][/row]
End of dataview
Adding line breaks and page breaks after a template grid in the document template does not add spacing between the sorted objects. If I try to add extra cells to my template grid in my document template and add page breaks or line breaks in there I receive errors.
You can't add page breaks to a template grid in a document template! Why i don't know?
Workaround:
Suppose you have a template grid with 25 records and you want a page break after 6 records. Create a helper entity which you can create in a microflow and refers to 6 records, create a new helper entity which refers to the next 6 records and so on. Display the helper entity on the document template.