I don't believe this has anything to do with your custom coding nor the rewrite rules but Laserfiche WebLink coding and logic.

For example, if you go to http://webdemo.laserfiche.com/WebLink8/Browse.aspx?startid=7 and click on the document entitled "Cities Digital Junxure Integration" (at the botom) look at the URL that is displayed whenever DocView.aspx has finished loading. You should see "http://webdemo.laserfiche.com/WebLink8/0/doc/531643/Page1.aspx".

Click the back button and now click on the folder entitled "Agenda Manager" and then click on the document entitled "Agenda Manager (3)". You should see "http://webdemo.laserfiche.com/WebLink8/DocView.aspx?id=531522" in the URL bar whenever DocView.aspx has finished loading.

Viewing the HTML source of these two links reveals a difference:

"Cities Digital Junxure Integration"

<a href="0/doc/531643/Page1.aspx" class="DocumentBrowserNameLink">
<nobr>
<img src="images/DocPage1.gif" class="DocumentBrowserNameImage">
<span>Cities Digital Junxure Integration</span>
<span class="EntryRowIconText">[Icon]</span></nobr>
</a>

"Agenda Manager (3)"

<a href="0/doc/531522/Page1.aspx" class="DocumentBrowserNameLink" onclick="__doPostBack('TheDocumentBrowser:_ctl58:_ctl5',''); return false;">
<nobr>
<img src="images/DocPage1.gif" class="DocumentBrowserNameImage">
<span>Agenda Manager ‎(3)‎</span>
<span class="EntryRowIconText">[Icon]</span>
</nobr>
</a>

What stood out immediately was that the "Agenda Manager (3)" link contains an onclick event handler while the "Cities Digital Junxure Integration" link does no contain it. This is why you sometimes get the "DocView.aspx?id=" link. When the link is a pure HTML link then it's handled through the URL Rewriter but when it has a JavaScript callback it's not.

Basically, it appears to be a logic bug because anytime you access "Browse.aspx" without clicking through folders and click on a document within the root of that folder it will always show a rewritten URL. However if you access that same file via clicking through folders to get to it then it's going to show the non-rewritten URL.

Example:

1. Click http://webdemo.laserfiche.com/WebLink8/Browse.aspx?startid=524401
2. Now click on "Agenda Manager (3)". You should see "http://webdemo.laserfiche.com/WebLink8/0/doc/531522/Page1.aspx"
3. Now click http://webdemo.laserfiche.com/WebLink8/Welcome.aspx
4. Click "Product Brochures" link
5. Click on "Agenda Manager" folder
6. Click on "Agenda Manager (3)". You should see "http://webdemo.laserfiche.com/WebLink8/DocView.aspx?id=531522"​

The following code has not been thoroughly tested but may help in this problem with the URL changing. Open up "Browse.aspx" and right before the "</body>" tag copy and paste the following:

<script type="text/javascript">
    document.body.onclick = function (e) {
        e = e || event;
        var from = findParent('a', e.target || e.srcElement);
        if (from) {
            /* it's a link, actions here */
            window.location = from.href;
        }
    }
    //find first parent with tagName [tagname]
    function findParent(tagname, el) {
        if ((el.nodeName || el.tagName).toLowerCase() === tagname.toLowerCase()) {
            return el;
        }
        while (el = el.parentNode) {
            if ((el.nodeName || el.tagName).toLowerCase() === tagname.toLowerCase()) {
                return el;
            }
        }
        return null;
    }
</script>

Save the file and reload it in your browser. Hope this helps!!