Multisport synchronisation issue

Hi. 

I participated in the full distance Ironman challenge Roth yesterday and I can find it on my watch. But it is not being synchronized by Garmin connect or express. Since it's such a big event I really want to look at and share my stats. I have cleared and reset my phone multiple times. I have uploaded another activity( short walk). Wich uploaded perfectly fine.

Weirdly enough if I look at stress it does show all the individual activity logos. 

How do I get the activity off my watch and on to the internet? And is this preventable in the future? It should not be an issue on such an expensive and dedicated to multisport device?