Sometimes SIMS temp files will not clear properly after use and this can cause issues such as not being able to run or open reports.
Below is a guide on how you can clear these files yourself.
1. Navigate to your file area in file explorer and look for a folder called tempSimsRpt
2. Open this folder and press CTRL+A and then the delete button. This will then clear the temp files and you should then find you can now open reports
3. If that does not work or you cannot delete all of the files, restart the device.