I'm not a LibreOffice user, but my guess if the instances won't convert is that they're not regular hyphens, but optional or nonbreaking hyphens. If they're only two instances, the easiest way to deal with it is manually. You can get an em-dash by holding down the Alt key and typing 0151 on the number pad. If that doesn't work, toggle NumLock and try again.
![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
timeasmymeasure
no subject