Krzysztof, I think one of the plugins must have changed something when it comes to capabilities.
I suggest 3 things, tested one by one.
1. Deactivate News Manager and activate it again.
2. Install user role editor to check if you have ‘publish_news’ capability.
3. Remove (or comment) line 581 in news-manager.php that’s responsible for news menu position
'menu_position' => 5,
Hope this helps.