Context: There have been numerous recent calls for research on the human side of software engineering and its impact on various factors such as productivity, developer happiness and project success. An analysis of which challenges in software engineering teams are most frequent is still missing. As teams are more international, it is more frequent that their members have different human values as well as different communication habits. Additionally, virtual team setups (working geographically separated, remote communication using digital tools and frequently changing team members) are increasingly prevalent. Objective: We aim to provide a starting point for a theory about contemporary human challenges in teams and their causes in software engineering. To do so, we look to establish a reusable set of challenges and start out by investigating the effect of team virtualization. Virtual teams often use digital communication and consist of members with different nationalities that may have more divergent human values due to cultural differences compared to single nationality teams. Method: We designed a survey instrument and asked respondents to assess the frequency and criticality of a set of challenges, separated in context ”within teams” as well as ”between teams and clients”, compiled from previous empirical work, blog posts, and pilot survey feedback. For the team challenges, we asked if mitigation measures were already in place to tackle the challenge. Respondents were also asked to provide information about their team setup. The survey included the Personal Value Questionnaire to measure Schwartz human values. Finally, respondents were asked if there were additional challenges at their workplace. The survey was first piloted and then distributed to professionals working in software engineering teams via social networking sites and personal business networks. Result: In this article, we report on the results obtained from 192 respondents. We present a set of challenges that takes the survey feedback into account and introduce two categories of challenges; ”interpersonal” and ”intrapersonal”. We found no evidence for links between human values and challenges. We found some significant links between the number of distinct nationalities in a team and certain challenges, with less frequent and critical challenges occurring if 2-3 different nationalities were present compared to a team having members of just one nationality or more than three. A higher degree of virtualization seems to increase the frequency of some human challenges, which warrants further research about how to improve working processes when teams work from remote or in a distributed fashion. Conclusion: We present a set of human challenges in software engineering that can be used for further research on causes and mitigation measures, which serves as our starting point for a theory about causes of contemporary human challenges in software engineering teams. We report on evidence that a higher degree of virtualization of teams leads to an increase of certain challenges. This warrants further research to gather more evidence and test countermeasures, such as whether the employment of virtual reality software incorporating facial expressions and movements can help establish a less detached way of communication.