1) When clients have multiple projects, they are not able to filter by project. It just automatically applies a filter for both projects. If you specify a specific area then the filter starts working b/c the area is unique to the project.
2) Clients are not able to save filters. This is annoying when they have multiple projects.
A client cannot make changes to an issue that they have raised themselves. Would be pretty handy when they need to edit mistakes or add additional information.