Entering melisma into lyrics

I am trying to add melismas into my lyrics in MuseScore4. According to the online user's guide:

If the melisma is at the end of a word it should be notated by an underscore line:
Starting from the end of the previous syllable, press _ (underscore) for as many notes as the melisma extends.
If a melisma occurs in the middle of a word it may be notated by hyphens instead:
Starting from the end of the previous syllable press - (hyphen) for as many notes as the melisma extends.
For long melismata, instead of repeated typing of hyphens, select the last note in the melisma and press - (hyphen). The intermediate hyphens will automatically be inserted between the previous typed syllable and that final note.

I followed these instructions carefully, however whenever I press _ (underscore) or - (hyphen) while in lyric input mode, the input box just jumps to the next measure, without adding the melisma.