.htaccess redirect loop when trying to transform last part of URL to fragment

I have the following rule in my .htaccess file.

RewriteRule ^(segment1|segment2)/(.*)$ $1/#$2 [R=301,NE,L]

The intent is to prepend a # to the last part of the URL. But I run into a redirect loop issue. I don't know why as I applied L flag.

What I want to achieve is, for example:

Turn:

http://example.com/segment1/test

into:

http://example.com/segment1/#test

Any advice would be much appreciated!

Thanks!