There are a number of patches to make SMS send on a long press (example, another) to prevent accidental sending. Are you sure you don't have one of them installed?
[root@Sailfish nemo]# pkcon install jolla-xt9 Command failed: This tool could not find any available package: could not find jolla-xt9
[root@Sailfish nemo]# ssu lr Enabled repositories (global): - adaptation-community ... http://repo.merproject.org/obs/nemo:/testing:/hw:/oneplus:/onyx/sailfishos_2.0.5.6/ - adaptation-community-common ... http://repo.merproject.org/obs/nemo:/testing:/hw:/common/sailfishos_2.0.5.6/ - apps ... https://releases.jolla.com/jolla-apps/2.0.5.6/armv7hl/ - hotfixes ... https://releases.jolla.com/releases/2.0.5.6/hotfixes/armv7hl/ - jolla ... https://releases.jolla.com/releases/2.0.5.6/jolla/armv7hl/ Enabled repositories (user): - openrepos-Almindor ... http://sailfish.openrepos.net/Almindor/personal/main - openrepos-Ancelad ... http://sailfish.openrepos.net/Ancelad/personal/main - openrepos-Buschtrommel ... http://sailfish.openrepos.net/Buschtrommel/personal/main - openrepos-Dax ... http://sailfish.openrepos.net/Dax/personal/main - openrepos-Larswad ... http://sailfish.openrepos.net/Larswad/personal/main - openrepos-Penguin ... http://sailfish.openrepos.net/Penguin/personal/main - openrepos-Schturman ... http://sailfish.openrepos.net/Schturman/personal/main - openrepos-anig ... http://sailfish.openrepos.net/anig/personal/main - openrepos-basil ... http://sailfish.openrepos.net/basil/personal/main - openrepos-coderus ... http://sailfish.openrepos.net/coderus/personal/main - openrepos-eugenio ... http://sailfish.openrepos.net/eugenio/personal/main - openrepos-llelectronics ... http://sailfish.openrepos.net/llelectronics/personal/main - openrepos-lpr ... http://sailfish.openrepos.net/lpr/personal/main - openrepos-ovekaaven ... http://sailfish.openrepos.net/ovekaaven/personal/main - openrepos-saberaltria ... http://sailfish.openrepos.net/saberaltria/personal/main - openrepos-vasvlad ... http://sailfish.openrepos.net/vasvlad/personal/main - store ... https://store-repository.jolla.com/onyx/armv7hl/?version=2.0.5.6 Disabled repositories (global, might be overridden by user config): Disabled repositories (user): - home ... https://download.jollamobile.com/home:/honeybadger/latest_armv7hl/