Limitations and problems with copy-pasting syllables of lyrics into rests
1) Although MuseScore allows to manually insert a lyric-syllable under a rest (from a measure) (by CTRL+L and then writing that syllable), it doesn’t allow to paste a syllable (copied from another note by left-clicking that syllable and then CTRL+C) to such a rest (not by double-clicking and then selecting “all text”: a more laborious double-step process).
2) Furthermore, even if I copy a syllable from one note (by left-click and then CTRL+C) and then insert a blanc syllable (with CTRL+L) in a rest and press CTRL+V, MS doesn’t paste that copied syllable to that chosen new rest (as if the clipboard doesn’t function in this case). Optional lyrics can be inserted under rests (sometimes with lyrics in parentheses) in some scores and I think the copy-paste function should also function when trying to copy a syllable from a note to a rest: correcting this issue would spare a lot of time in the process of copying syllables from one note to a rest from the same or another staff.
3) Curiously, when I choose two consecutive syllables, copy them (by selecting them with pressed CTRL and then left-click on both) and try to paste them on two consecutive rest (with same duration), they are pasted at distance from those rests and NOT exactly on the correct positions (right under those rests): this is another issue. It is thus curious that this type of copy-paste doesn’t work on single syllables but works on multiple syllables (although it wrongly positions those pasted syllables).