Hi Alide Folz

Before I offer some possible root causes, please allow for me to clarify that it is best practice for the Trados Live Projects to be accessed from within Trados Studio at project level.
From within the live project you will find all the actual *.sdlxiff files at files view which then takes you to the editor view. 

While I dont know what version of Studio you are using, or details around the live-cloud, perhaps this article can point you in the right direction: 
https://gateway.rws.com/csm?id=kb_article_view&sysparm_article=KB0036814

The key takeaways are are:
1. Authentication from Studio to the Trados Live Account when retrieving the project 
2. If anything, repair of Trados Studio

If non of this helps, please let me know so I can help investigate further for you

Regards

Lydia