Spell check only kicks in after the space bar is hit after a misspelled word. If the enter bar is hit then there is often no indication of a typo.
If you have a full line of typos and delete that space character at the end of the line it will sometimes remove all typo indicators and only restore them after hitting space at the end of a line.
Playing around with it the behavior is inconsistent, but pops up enough to be frustrating when proofing a sermon.
