Unfortunately for my ubuntu 18.04 LTS and this is in no way Signal's fault (but maybe the desktop version doesn't have that bug ?):
$ apt-cache policy signal-desktop signal-desktop: Installé : 5.10.0 Candidat : 5.10.0 Table de version : *** 5.10.0 500 500 https://updates.signal.org/desktop/apt xenial/main amd64 Packages 100 /var/lib/dpkg/status 5.9.0 500 500 https://updates.signal.org/desktop/apt xenial/main amd64 Packages 5.8.0 500 500 https://updates.signal.org/desktop/apt xenial/main amd64 Packages
$ apt-cache policy signal-desktop-beta signal-desktop-beta: Installé : (aucun) Candidat : 5.11.0-beta.1 Table de version : 5.11.0-beta.1 500 500 https://updates.signal.org/desktop/apt xenial/main amd64 Packages
Unfortunately for my ubuntu 18.04 LTS and this is in no way Signal's fault (but maybe the desktop version doesn't have that bug ?):