If you are getting an error "Remote Invocation Failed, Due to Status Code:" while searching records or downloading the files is specifically because you do not get a status code back due to local network connectivity issues.
Basically, it is sporadic because it is probably tied to infrequent network issues at your end where the app can't make a call out to download the files from the Salesforce account to your browser/machine.

  Try switching to another network and reload the page.