Automotive companies increasingly adopt scaled agile methods to allow them to deal with their organisational and product complexity. Suitable methods are needed to ensure safety when developing automotive systems. On a small scale, R-Scrum and SafeScrum are two concrete suggestions for how to develop safety-critical systems using agile methods. However, for large-scale environments, existing frameworks like SAFe or LeSS do not support the development of safety-critical systems out of the box. We, therefore, aim to understand which challenges exist when developing safety-critical systems within large-scale agile industrial settings, in particular in the automotive domain. Based on an analysis of R-Scrum and SafeScrum, we conducted a focus group with three experts from industry to collect challenges in their daily work. We found challenges in the areas of living traceability, continuous compliance, and organisational flexibility. Among others, organisations struggle with defining a suitable traceability strategy, performing incremental safety analysis, and with integrating safety practices into their scaled way of working. Our results indicate a need to provide practical approaches to integrate safety work into large-scale agile development and point towards possible solutions, e.g., modular safety cases. Keywords: Scaled Agile, Safety-Critical Systems, Software Processes, R-Scrum, SafeScrum