When Custom SQL views exist in a database, especially one-to-many, the Combine Student Records process can error out. The process may 'spin' for a long time. We have identified the issue and will be working on a fix as soon as possible. In the meantime, the only work around is to delete the Custom views from the Custom Tables definitions and then re-add them after the process has run.
Users may receive updates about the status of the fix here https://ideas.aeries.com/forums/926386/suggestions/43262469