Launcher badges are not native to Android and will not work on every device/launcher. Pulse SMS uses this framework to enable them, and should work on the devices/launchers listed below.
If it is showing an incorrect count, you can mark all the messages as read by tapping the double checkmark button in each date category on the Conversation list. If you can't see the date categories, head to Settings > Theme, and enable Display Date Categories.
If the badge still displays an incorrect count, that launcher is probably trying to read the unread count by itself instead of respecting what Pulse SMS provides. If you open up the stock/native SMS app that came with your phone, set it as the default messaging app, then make sure everything is marked as read there, it should fix your issue and start displaying an accurate count for Pulse SMS.
As of Android 8.0 (Oreo), most launchers have opted for a notification dot instead of the traditional unread count badges.
Supported Launchers
- Nova launcher with TeslaUnread, Apex launcher, ADW Launcher provided by notz
- Solid launcher provided by MajeurAndroid
- KISS Launcher provided by alexander255