@UWPVIOLATOR correct, once the client finishes running the snapin another process seems to still be using it (according to the log). You can use a utility called Process Explorer (https://docs.microsoft.com/en-us/sysinternals/downloads/process-explorer) to check. Please check for the lock right after/when the client produces that error message (or as soon as possible after it occurs).
For more info on using that tool: https://www.techsupportalert.com/content/how-find-out-which-windows-process-using-file.htm