I'm using K2 v2.3 , tried numerous current SH404sef vers. including stable and beta and joomfish v2.0.4 with joomla 1.5.18.
Here is the issue as best as I can explain it, maybe someone can duplicate this.
I have a single k2 category (projects), all articles are using tags to organize the content in 2 ways (location= 6 tags) and (service= 6 tags). The articles will always contain at least 1 location tag and 1 or more service tags.Ok so now I set up my menu with Projects and sub menu's with location and service then menu items below those that are tag based menu items.K2 category list view--->       Projects__                K2 single item view--->       Location___                                         K2 tag list view--->       USA                                         K2 tag list view--->       Europe                                         K2 tag list view--->       Asia                                         K2 tag list view--->       Africa                                         K2 tag list view--->       Latin Amercia                                         K2 tag list view--->       Worldwide                K2 single item view--->       Service___                                         K2 tag list view--->       line 1                                         K2 tag list view--->       line 2                                         K2 tag list view--->       line 3                                         K2 tag list view--->       line 4                                         K2 tag list view--->       line 5                                         K2 tag list view--->       line 6OK now that we have the structure when I navigate to a K2 tag list view and change my language setting via the JFlanguage module, then click on the intro text title to view the article or the read more link the resulting article view is missing the itemId so no modules associated with that itemId render on the article view.I believe I have the correct settings on SH404sef, I've been using it on a lot of sites for a long time. ItemId settings are correct.Is there an issue with the sef_ext that K2 has included? Can anyone take the time to confirm this issue?I am at a total loss here.tia,Apple

After further testing I have found that the problem lies with joomfish and K2.
After turning off SH404sef, I still am having the issue.

When I go just to a K2 category list view (Projects), then use the language selector via mod_jflanguageselection to go to Spanish, everything is ok. url=
index.php?option=com_k2&view=itemlist&layout=category&task=category&id=9&Itemid=55&lang=es

But If I click the same menu item (Projects) in spanish the url changes and I no longer have the Cat list view. url=
index.php?option=com_k2&view=itemlist&layout=category&task=&id=&Itemid=55&lang=es

index.php?option=com_k2&view=itemlist&layout=category&task=&id=&Itemid=55&lang=es

then after that If I click back to english it gets even worse url=
index.php?option=com_k2&view=itemlist&layout=category&task=&id=&Itemid=55&lang=us

This is totally repeatable and easy to check out.
any thoughts?

ok this seems to be the content handler for K2 menu items
menu.xml
Can the devs please check this out as I have seen this issue prior to 2.1
there was a manual fix that didn't get included in 2.2 and know there is a new version of the menu.xml in v2.3
But it seems to not be a complete solution.
please see this thread...
community.getk2.org/forum/topics/joomfish-menu-translation?commentId=3536014%3AComment%3A11827

The issue is still present even with the new menu.xml in v2.3.