Hi Tom,
Since the keyboard works normally in other apps, this does appear to be specific to how Word is processing the spacebar input.
Could you confirm whether it happens in every Word document, including a completely new blank document? Also, does it occur only after typing a word or does a quick press of the spacebar fail even on an empty line?
If it happens in all documents, please share the Samsung phone model, Android version and Word app version. Since the usual device and app troubleshooting has already been completed, the next practical step would be to report the behavior through Word’s in-app feedback option with those details, along with the K06 keyboard model and the approximate date the problem started. This may be a recent app-specific compatibility issue that requires further investigation.
In the meantime, Word for the web can be used in the phone’s browser as a temporary workaround if the spacebar works normally there.
Please let me know what happens in a new blank document.