There are several problems with open plan office space for tasks that require concentration and little spontaneous interaction – such as many administrative tasks and much research much of the time in law, political science, philosophy…
This is of course not to deny that open plan office space may be overall conducive for some other sorts of work. But the findings require extensive attention to a wide range of variables, including the nature of the tasks, work environment, etc.
1 Reduced productivity due to inability to concentrate
Insufficient privacy in the workplace is an issue throughout the world. Being able to concentrate, work in teams without being interrupted or choose where to work based on the task are frequently unmet needs.
A metastudy by organizational psychologist Matthew Davis, reviewing more than a hundred studies about office environments, concludes that
though open offices often fostered a symbolic sense of organizational mission, making employees feel like part of a more laid-back, innovative enterprise, they damage workers’ attention spans, productivity, creative thinking, and satisfaction. Compared with standard offices, employees experienced more uncontrolled interactions, higher levels of stress, and lower levels of concentration and motivation. 
2 Blocking sound with music doesn’t help
Psychologist Nick Perham studied the effect of sound on how we think: Office commotion impairs workers’ ability to recall information, and even to do basic arithmetic. Listening to music to block out the office intrusion doesn’t help: even that, Perham found, impairs our mental acuity.
There are several, partly contradictory findings concerning open offices and health. The Norwegian Directorate of Health has a review (in Norwegian). Jan Pejtersen and colleagues studied more than twenty-four hundred employees in Denmark and found that workers in two-person offices took an average of fifty per cent more sick leave than those in single offices, while those who worked in fully open offices were out an average of sixty-two per cent more., 
Psychologists Gary Evans and Dana Johnson found that clerical workers who were exposed to open-office noise for three hours had increased levels of epinephrine (adrenaline) associated with the so-called fight-or-flight response. 
 Drawn/plagiarized from several sources:
For a review of the literature on health effects, from the Norwegian Directorate of Health (in Norwegian): Here.
For a (meta) metastudy on Open office studies and their subjects of study: A Gjerland, E Søiland and F Thuen 2019: “Oﬃce concepts: A scoping review” Building and Environment 163 https://doi.org/10.1016/j.buildenv.2019.106294
 Ipos, the Steelcase Global Report https://www.steelcase.com/research/articles/privacy-crisis/
 Davis, M. C., Leach, D., & Clegg, C. (2011) The Physical Environment of the Office: Contemporary and Emerging Issues. In Hodgkinson, G. P. & Ford, J. K. (Eds.) International Review of Industrial and Organizational Psychology (Vol. 26, pp. 193 – 235). Chichester, UK, Wiley.
 N Perham, H Hodgetts, S. Banbury. “Mental arithmetic and non-speech office noise: an exploration of interference-by-content.” Noise Health. 2013 Jan-Feb;15(62):73-8. doi: 10.4103/1463-1741.107160.
 Pejtersen, Feveile, Christensen and Burr: Sickness absence associated with shared and open-plan offices–a national cross sectional questionnaire survey.”Scand J Work Environ Health. 2011 Sep;37(5):376-82. doi: 10.5271/sjweh.3167. Epub 2011 Apr 28.
 Summary in Danish: https://www.mellomrom.no/single-post/2016/03/18/Åpne-kontorlandskap-–-forbannelse-eller-velsignelse