Human Research Ethics Committee (HREC) reviewers often provide similar feedback across applications, which suggests that the problem lies in researcher awareness of key issues rather than novel, unsolvable challenges. If common problems can be addressed before lodgement by applicants referencing clear evidence-based supports (e.g., FAQs on common application shortcomings), it would improve efficiency for HREC members and expedite approvals. We aim to inform such supports by analysing the patterns in the most frequent feedback made by HREC members during review processes. We collected every instance (N = 4,195) of feedback made on N = 197 'low-risk' protocols by all HREC staff (N = 16) at one institution over the course of a full year (2019). Reflexive thematic analysis to identify themes (and content analysis to determine relative frequency) revealed that the top three themes are consistent with existing literature: Consent, Administrative, and Methodological concerns. However, we identified important new themes that are not captured in previous research, including 'Risk to Researchers', 'Commercial benefit, scope and scale', 'Diversity' (covering issues of cultural sensitivity, language and accessibility), as well as fair right to a complaints process. Our thorough exploration of information-rich primary data marks an important methodological improvement over previous studies and offers a theoretical contribution to understanding themes that have heretofore been overlooked in the ethics review process. By identifying the common challenges experienced in HREC review we can better inform tailored supports to applicants (by extension reducing workload burdens on HREC systems) and reduce their perceived barriers to engaging in challenging but meaningful research.