Whenever I try to add a Digital ID, the ID appears in the list of Digital IDs but only until I close the window with the list. Then when I open the list of Digital IDs again, the list is blank. It seems like it doesn't actually save the Digital ID anywhere.
This issue could be related to security settings for the CertFile folder. We could access C:\Users\[UserName]\AppData\Roaming\Foxit Software\CertFile, then double-click on this folder to check if you have been denied permssion to access the file. If you don't have permission for this folder, you may get the following error:
To gain access for the folder, we could right-click on the CertFile folder then open Properties > Security > Advanced > Change > input the user name in the Enter the object name to select field > Check Names > OK. After taking ownership of the folder, we should see the Digital IDs stay saved.