Writer Mail Merge hanging

I continue to be plagued with problems making the mail merge function operate properly in the Writer module.

I did finally get it to work with a form letter, but only when I created New Document. Using an existing document would just hang.

Now, when I try to print labels, it just hangs when I go to File > Labels, link my spreadsheet, and click New Document.

I saw references to needing JDK installed. I have tried both JDK 8u111 and JDK 8u112, but neither one does the trick.

I was using LibreOffice 5.1.6.2 on Windows 8.1.

I just tried upgrading LibreOffice to 5.2.3.3, but it did not help.

Suggestions?


Edit: one hour later

After I let it spin for about 5-10 minutes, I just gave up and went out on an errand.

When I got back an hour later, the process had finally finished successfully to build the label pages.

I have no idea why it took so long, but at least it finished.