The template invocation must have a terminating /span. This test confirms that the sandbox version adds the span correctly, whereas the live version when I first tested this does not terminate the span, so that Dirac is also included in the span container in the generated html (look at the page source to see this).

Sandbox version edit

{{Gaps/sandbox|P.|A.|M.}} Dirac

P.A.M. Dirac

Main template edit

{{Gaps|P.|A.|M.}} Dirac

P.A.M. Dirac