I was recently working with name tags from Avery Templates in InDesign. One of the things I wanted to do was automatically import the data into InDesign with a CSV file. There are many tutorials on the web that explain the process (this article by GCO Studios is great). However, I was running into an issue with multiple records not loading in. Try and check the following:
Have only one instance of the item that is going to be copied remaining on the page.
You can do this easily without affecting your existing document.
Group your elements.
Create a new document with the final document size to be printed.
Paste in Place (Cmd + Shift + Alt + V).
Make sure you are working on the final document size to be printed.
i.e. if the final template is a name tag slide with 6 badges on a letter document, your document size should be letter-sized.
Place a box with a border and the exact size around your elements.
This helps with the layout and determine where overflow may be taking place. If you want, you can place the box on a separate layer that you can toggle on/off.
Ensure your margins, column spacing, and row spacing are accurate.
Have one manually laid out document on screen as a reference
Start with zeroed out values and increment slowly to adjust
Avoid stray graphics. Create a separate document for repeating.
This goes hand in hand with the boxing advice. InDesign is assuming all the elements are going to be repeated. It draws an invisible container and repeats across with your specifications. Then it proceeds to fill the data in. However, if you have stray graphics, that invisible container is going to be larger than your repeating object, preventing it from rendering correctly.
Make sure your spreadsheet is clean
Check your spreadsheet before hand for stray characters. This can cause overflow problems (use Auto Text Sizing).
InDesign does not process line breaks in Data Merge. If you need line breaks, use a non-standard character to replace all line breaks. Then after merging, use Find and Replace to replace all your non-standard characters with line breaks.
And of course, don't just trust the computer! Do a manual review of your document. You can always customize after the merge. It's all InDesign elements, ready for your handiwork. And then, test print as well. There are little quirks that Avery templates alone won't help you with (embossings, specialized die cuts, etc.).
I recorded a quick screencast demonstrating a small problem with Multiple Records and subsequently fixing the issue: