If you get several notices of new Followers however your count is staying the same please read the following carefully.
The perception of followers not growing comes because we send notifications when people follow you, but not when users 'unfollow' you. This means in the same time that people follow you (which you're notified for), other followers may have un-followed you, which would lead your followers count not increasing by the amount that you were notified for.
The problem is that there is a delay for this action to have an effect on all the accounts the spam account followed meaning that the actual number of your Followers will take time to adjust while our system reverts all Follow actions made by the spam account.
An important note on the severity of spam: we remove 1,000's of spam accounts daily which has a huge impact on user followings.
How do you know if your account is being followed by Spam accounts? Take a good look at your Followers. Do you see many blank accounts? Accounts with no image or a username like User1234455? Also, do you see patterns in the images such as images provocative in nature? These are likely spam accounts. You can help us detect these fake accounts quicker by blocking and reporting them.
Our team is working hard to make the actions of spam accounts revert immediately to decrease the misconception of stuck followers.
Thank you for your reading. We will continue to monitor this issue closely.
-Mathis and Gina