hubsell decided to add the attention feature to help the flow of your campaign. There can be various reasons.
For example: Sometimes your campaign is trying to message the non-connected LinkedIn prospects. (it is not possible to send a message via LinkedIn without completing the first step i.e to connect with the prospects)
Now the system pushes this activity multiple times in a row. To avoid the hindrance and to keep the flow of your campaign, these contacts will automatically get pushed to the attention page.
In order to move those contacts to your running campaign, please take the following steps:
go to attention in your campaign page
select all the contacts via the check boxes on the left
click mark as resolved in the right side panel
Once you do that, these contacts will be transferred to your campaign's contact page and the sendings will go smoothly :)