To resolve the issue please follow the below mentioned steps:
1. Open Setting > General Management > language and Input > On Screen Keyboard > Samsung keyboard > About Samsung keyboard > Update (If Available).
2. Go to Setting > Apps > tap on three dots > tap on show system apps > Samsung keyboard > Storage > Clear Data > Delete > tap on Back key > Force Stop.
3. Open Setting > General management > Reset > Reset setting > Reset setting.
For further assistance, register your concern in Samsung members app(Open Samsung members app>click on “+“icon>send feedback>Error report/ Ask Questions).
Team Samsung Members