On the deployment health checks dashboard, do you also Fail the health checks for Hidden Actions? You may actually have 17,000 open actions, just you can’t see them all in the console.
Otherwise, check the folder ID’s against the downloadcleanerdata.txt file and see if they are in the text file. If they aren’t in the text file, then we need to figure out why, the tool queries the database to get the ID list so either the query is wrong or the actions are still open and shouldn’t have their download folder deleted yet.
The DownloadCleaner tool referenced here is for removing a much of folders but the amount of data in each folder is very small, a few KB, so you aren’t going to reclaim much disk space with this tool. If you aren’t failing the health check, you shouldn’t run this tool and so it isn’t referenced on the standard utility list which is here: