Since your client is not sharing any code what so ever, there is no genuine way for us to help you with this question (which should have been closed initially since it’s centered around a third-party plugin).
Now, with that being said, to troubleshoot this, I would look into the following:
- Check if your CSS styling is in order. It may be a case of incorrect styling for the boxes, making the first one being in its own line. This is very likely the issue. Look into how to stack divs in a pinterest type of layout. There are a variety of options, and some of which may conflict in your current layout.
- Check the source of the outputted page (view source). Is the first box any different than the other ones. If so, that is very likely why it is on its own line. If all are identical in their div architectural structure, move on to the next step.
- Look into the actual source of code that generates the list of divs. What can you find there? Does the code add any particular classes to the first box? etc.
Trust me, this is as good as it gets without seeing the code.