K2 modules may conflict with 3rd party components (some of ours as well) which contain item.php file in models folder.
This is related with function addIncludePath of JModel and that K2 system plugin doesn't use prefix as a second parameter of this function. In result the path to K2 models is added only to global prefix where all other paths are also added usually after K2 path. Consequently getting the instance of the model include the item.php only from last added path which is not K2 and generates the warning message that K2ModelItem class was not found in file.
Our K2 fix plugin adds the models path with K2Model prefix what fix major problems with proper working of K2 modules with other extensions. It fixes following problems in certain modules:
- K2 Content - module doesn't show up and warning message is displayed: Model class K2ModelItem not found in file
- K2 Users - nothing except php error message: Fatal error: Call to a member function getUserProfile() on a non-object in components\com_k2\helpers\utilities.php on line 65
- K2 User - white page after log in
- K2 Comments - it seems to work, but warning message is displayed: Model class K2ModelItem not found in file