Or it might just be that some people are introverted and crack under pressure whenever the spotlight is on them but, once they have quiet time to themselves, they can really power through problems.
The description of the scenario isn't nearly enough for us to get any grip on what was going on without making some huge assumptions, but the facts that we have are that she tended to really struggle when coordinating with coworkers and that she completed the work expected of her - there could be numerous explanations and the observations from the poster might even be inaccurate.
It's a story a friend told me a long time ago. I didn’t and couldn’t fact-check it. The husband’s theory came from the fact she apparently mentioned her husband was also a software consultant.