IIS URL Rewrite causes infinite loop

I wrote a simple URL Rewrite rule for the IIS URL Rewrite component. It is working, but there is also a weird infinite loop thing going on when I load the page.

We don't have a certificate on this domain, so to load the URL you have to add an exception to your browser.

Here is my test URL:
https://ephoton.domain-group.com/catalog/123/Category-Title

Here is my web.config file:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
	<system.webServer>
		<httpErrors errorMode="Detailed" />
		<rewrite>
			<rules>
				<rule name="catalog">
					<match url="^catalog/([0-9]+)/([_0-9a-z-]+)" />
					<action type="Rewrite" url="catalog.htm?id={R:1}&amp;cat={R:2}" />
				</rule>
			</rules>
		</rewrite>
	</system.webServer>
</configuration>

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Is there something wrong with my rule?

The resulting page should show the two values I am trying to capture:
ID=123
Cat=Category-Title

Thank you.