Interesting - I thought that maybe there was some incompatibility with intervals.icu, or that I’d done something wrong, and that was why i wasn’t getting out of zone alerts. So I agree with the far-blue, that this is something that should be supported in guides. An additional complication is that the display of phased workout information is very small, and not easy to read (Vertical).
While it’s great that Suunto has support for a whole bunch of different training platforms, out-of-zone alarm functionality should really be present. And the display of info for phased workouts could be much more legible.