The error that you are receiving is know issue but it has a work-around.
To have your Salesperson Preview List appear, the URL address of the list will need to be edited after the error has been generated. Once the text of the address has been changed, you can "re-enter" the address and your list will be available with all of the proposed changes that you had previously made. None of your hard work has been lost.
To be able to re-open you Salesperson Preview List, please do the following -
1. You will have a URL address similar to the following, highlight and delete the text from the word "Error" through to the word "admin" -
-- https://WAAA.matrixformedia.com/Error/FileNotFound?aspxerrorpath=/admin/SalespersonPreview/Show/9234688
2. Add in the word "manager" between the forward slashes after the .com and before the SalespersonPreview....
-- https://WAAA.matrixformedia.com/manager/SalespersonPreview/Show/9234688
3. Enter
...And your Salesperson Preview List will appear.
4. Continue to work as normal
If you do not finish up with your list, this will have to be done each time that you work on it...until you execute the changes or decide that you do not want to use the list and delete it.