After deploying a new release such as a hotfix release, sometimes overlooked is whether there are Customizer changes that are now in conflict with the new release. This can be identified by logging into the Alliance Browser as a customizer, going to the Customer menu and using the Conflict Resolver.
If there are conflicts, they will be listed and you can select which conflicts to resolve. When this is completed, the resolved conflicts are placed into the DEV branch (not Public) for you to review and accept.
When the changes are accepted in the Dev branch, publish the Customizer changes again to make them available for other users.
This should be done every time after a deployment of new releases to avoid issues caused by missing Customizer customizations.