if your unable to find it, submit an error report on SSM after replicating the issue
Samsung Members app > Get help > Send feedback > Error reports
Try this. Go to your Settings > General Management > Samsung Keyboard Settings > Reset to default > Reset keyboard > Reset.
If steps above didn't work then go to Settings > Apps > Tap the icon the looks like a tower on the right side of the word that says " Your apps" then enable show system apps. Then look for Samsung Keyboard on the list of apps then Storage and then Clear Data.
These steps should fix your issue.