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Doesn't sound right tbh. I'll be the first to moan about the Suunto app but uploading activities and syncing across to Strava is one thing it does fast and reliably. There are a load of articles online, and you could try customer support before returning it.
FWIW I uploaded a run from lunch time earlier and it went straight over to Strava so seems unlikely to be a service outage or something like that.
You could try disconnecting it from Strava and reconnecting? Then record a brief activity and try uploading again. I've only had issues like you describe once and I think it was a Suunto issue with their service in the end. It's normally very reliable.
You can download the activity from Suunto and upload to Strava manually so you don't lose a run but obviously not something you want to be doing for every run!