Yes, this is a known problem. A fix requires some extensive revamp of the File Transfer mode and we have this on our roadmap. We will do our best to implement this as fast as we can, perhaps even this year.
It's weeks from now, but not too many. Initially, we planned to release version 6.9 much earlier. In fact it would have already been available at the moment. Then we decided to add quite a few important fixes and features - namely two-factor authentication. So it will take a while.
I had a total of about 8 machines that Windows Defender and Security Essentials had quarantined.
That might be the case, although Microsoft was very fast to fix the issue. We haven't been reported issues with Windows Defender since then.
We continue to send reports and communicate with a/v software vendors regarding false positive classifications. The problem is that nowadays almost all a/v software vendors heavily rely on machine learning algorithms which are very inaccurate. Alas, they don't care much about their customers who have to restore their lost data or installations after another erroneous detection.
2. Fill out the form. You may need to sign in to your Microsoft account.
3. In the lower part of the form make sure that you fill out the fields as shown in the attached screenshot. You can also upload the file rfusclient.exe. You can find it in the C:\Program Files (x86)\Remote Utilities - Host\ directory. If it's not there - restore it from Quarantine in Windows Defender settings.
4. Click Continue. On the next page confirm form submission.
P.S. Microsoft has always been quick to resolve FP issues. Let's see if they manage to fix this one asap.