Hi everyone, I have managed to find a solution.
I was having the same issue but mine was more severe as it was not showing any word suggestions, no auto correct, no auto punctuation. I was having to type everything out myself. Very annoying.
But I've managed to figure it out. You simply need to reset/restore the app. And the way to do this is to go to the app settings and clear all data.
So go to Settings>General management>Language and input>On-screen keyboard>Samsung keyboard. Click About Samsung keyboard. Now click the i icon in the top right hand corner. Click Storage, at the bottom of the screen you will see 2 options > Clear Data and Clear Cache. You want to click on clear data. Once this is done, your app is now reset/restored. It will now work as normal.
I hope this works for you. Let me know how you get on.
Worked for me thanks