I also faced the issue regarding files with “malware”. I worked around it by ignoring such files (at least Insync does not get stuck trying to download such files…).
Hi all!
For those still experiencing this error, could you send your log files to support@insynchq.com with the link to this post? https://help.insynchq.com/en/articles/1834816-locating-the-log-files
Please include a screenshot of the DownloadGDBlob errors on your app as well.
Thank you!
Yes, @sliddjur. If it’s too big as an attachment, you can send us a link to download and include a screenshot of the error in the app window. 
Ok I was able to compress the file to only 2MB. I hope you can find something so I can fix my sync issue.
I just sent you an email.
I see this thread is 8 months old. Within the past few weeks, I started having problems with this same error (in v1.5.7 on Windows 10 x64). Most of the errors are of the type “unhandled error” with a few errors showing as “This file has been identified as malware or spam and cannot be downloaded”.
Has Insync just walked away from any support? I’ve been emailing them privately concerning another problem and they’ve simply stopped responding. :^(