Hello Repentant,
There isn’t any known issue. By default, you can pause cinematics with a left-click ingame, alt-tabbing won’t have the same effect. If you missed some part of a cinematic, you can rewatch it using the “more” dropdown button.
If the left click doesn’t work, it could be caused by another program or a setting. In doubt, you can close background programs and reset your hotkeys settings.