Compare Blog settings > SEO tab with this blog
http://fairjustice.net/index.php/StudiesandLinks/washington/

Aside from the Main Page displaying post excerpts instead of full posts, everything else is identical. And if I change the other page to show excerpts on the main page, the "More>>" link doesn't work there either so it's apparently a site wide problem.

Then don't set Main Page to display excerpts. It's another known-but-never-fixed bug ;)

I posted a workaround on this forum some time ago. I can't find it, try to search posts by login name between 2008-2010

Ok, unfortunately it's kind of a must for this site...I'll see if I can find your workaround...

Search for "force_more", "content_mode", "intro_mode"

Ok, found it: http://forums.b2evolution.net/viewtopic.php?t=19044&highlight=contentmode

I replaced this:

// Default params:
$params = array_merge( array(
		'feature_block'   => false,
		'content_mode'    => 'auto',		// 'auto' will auto select depending on $disp-detail
		'item_class'      => 'post',
		'image_size'	    => 'fit-400x320',
	), $params );

with this:

// Default params: 
$params = array_merge( array( 
        'feature_block'   => false, 
        'content_mode'    => 'auto',        // 'auto' will auto select depending on $disp-detail 
        'item_class'      => 'post', 
        'item_status_class' => 'bPost', 
        'image_size'        => 'fit-400x320', 
    ), $params ); 

if( is_default_page() ) 
{ 
    $params['content_mode'] = 'excerpt'; 
} 

But it has not resolved the issue.

Ok never mind. Try this in _item_block.inc.php

// Default params:
$params = array_merge( array(
		'feature_block'   => false,
		'content_mode'    => 'auto',		// 'auto' will auto select depending on $disp-detail
		'item_class'      => 'post',
		'image_size'	    => 'fit-400x320',
	), $params );
	
if( $Blog->get_setting('main_content') == 'excerpt' && $disp != 'posts' )
{
	$params['content_mode'] = 'full';
}

Also, I need to be able to have some blogs display full contents while others display excerpts so if this is going to be a site-wide mod, it won't work... Should I go back to 3.3.3? Seems like 4 has some issues...

I didn't know you found it already :)
Anyway this can be done 2 different ways.

- The way I posted back in 2009 with "Standard post contents" selected in SEO tab
- With the code I posted now and "Excerpts" selected on SEO tab

The second solution fixes "more" button if you selected "Excerpts" option for "Main page". It's not a site-wide mod, it depends on what you checked in blog settings.

Going back to v3 won't solve the problem since it has the same behavior.

Freakin' AWESOME!