weird lyrics anomaly when replacing rest with note

[matevz]

Steps to reproduce:

1. write some notes and rests
2. add lyrics and add syllables to all notes
3. somewhere in the middle replace rest with a note
4. all syllables are shifted for one additional syllable and are not aligned anymore with notes. However, adding a note at very end resynchronizes the lyrics and it's fine.

Expected results.
When replacing a rest with note, an empty syllable is added and aligned below the newly added note. Other syllables are aligned with their previously aligned notes.