TLDR at the bottom.
Background:
So I started at my new workplace a little more than a month ago, I'm still in my 3-month-long probation period (Europe). I work work with people from all over the world, it's a highly international team. My boss and my other colleague are from differing countries. One of my colleagues, let's call her Sarah for the sake of anonymity, is from the same country that I am from and we have been kind of “assigned” to work together and get trained by her since it's probably easier due to no language barrier. Almost everyone works from home, and Sarah and I have to go to the office twice a week because we're in the same country and city and it's “nice to socialize”.
The problems:
Whenever I am in the office with Sarah, I feel anxious because she just can't stop complaining even though she feels content at this workplace in general, according to her. The worst part is that I hate those 2 days that I have to be with her in the office because we have to share a tiny, shoebox office room which means I have to listen to her all day long. This is one part of the problem.
The other problem is, she's just unable to brief me and hand information over. Every time I either get so much information that I'm confused or no information at all. I've tried several methods to just really get the info that I need. I've tried to convey the conversation in a way that would require her to summarize things, but it's just not working, she literally can't minimize the information or she keeps it to herself. This doesn't happen whenever my boss or another colleague explains something. I don't really think that she's not doing it on purpose though, but it's making me anxious and I feel like a dumb person because of this.
TL;DR:
New job, colleague complains all the time and either shares too much (confusing) info or no info at all.
The question:
How would you deal with a person who never gives you the context or the right amount of information to do your job?
Thank you in advance!