They have not been removed, they are simply not installed by default. This would not in general cause an issue, as the older version of the Visualizer could be used, however changes in version 4.5.2 have made it necessary to break compatibility with previous versions of Visualizers. To correct this issue you must update the Reporting Services and Chart Visualizers. In order to do this, use the following steps:

1. Log in as a Host user
2. Select "Add/Remove Extensions" from the action menu of any of your installed Reports modules
3. Click "Browse..." and select the Visualizer you wish to install. The packages are located in the DesktopModules/Reports/Install/Visualizers folder in your DNN Installation (you may need to either download these from your site, or manually extract them from a Reports Module Distribution ZIP if you are not viewing the page from your DNN site).
4. Install the Visualizer by clicking the Install Package link.

Your data should not be affected, but it is always prudent to back up before installing/updating modules/extensions. If you have a previous version installed (from 4.4), all of your settings will be correctly migrated to the updated version.

Future releases should not have this issue and upgrading should be a much smoother process in the future.

Andrew Nurse
DotNetNuke Core Team Member and Reports Module Project Lead
Microsoft Certified Professional Developer

That is essentially what the installer does, so that shouldn't cause an issue, glad you fixed your problem.

Just a side note though: You must be logged in as a Host user (aka SuperUser) to see the Add/Remove Extensions menu item (you must also use the drop down menu on the top left corner, it doesn't show up on the bottom of the module). Administrators cannot install Visualizers for the same reason they cannot install new modules, it would be a security risk.

Andrew Nurse
DotNetNuke Core Team Member and Reports Module Project Lead
Microsoft Certified Professional Developer