sign in issue

I had a similar issue happen a few months ago. Here are the instructions they supplied to me (the important steps for me were 3 & 4):

You can also follow the guide below to remove all Articulate 360 files and registry keys from your computer, so we can start completely fresh. This time, try to install the Articulate 360 app for administrative rights.

1) Close the Articulate 360 desktop app by right-clicking the Articulate icon in your computer's system tray (by the clock) and choosing "Quit."

2) Go to your Control Panel and uninstall all Articulate 360 apps, including the Articulate 360 desktop app, Peek 360, Replay 360, Storyline 360, and Studio 360.

3) Download and extract this zip file on your computer: http://articulate-360-kb.s3.amazonaws.com/360cleanup.zip

4) Right-click the 360cleanup.bat file and choose "Run as administrator." The script should only take a few seconds to remove all the Articulate files and registry keys from your computer.

5) Reboot your computer.

6) Download the latest Articulate 360 desktop app here: https://360.articulate.com/downloads

7) Right-click the articulate-360.exe file and choose "Run as administrator."

8) Launch the Articulate 360 desktop app and click "Install" beside each authoring app you want to install.

9) Reboot your computer and test your Articulate apps.

I hope that helps.