I emailed Suman about this problem before. On a fresh install I created a clone of my pool while it had no snapshots, and it caused an error page to come up when I tried to make scheduled snapshots. Suman said he committed a fix in 3.8-4, but my scheduled tasks page just spins the refresh icon in the middle forever since I updated.
Can you hard refresh the browser(shift+ctrl+r) and confirm this is consistent? If you open the browser console, there should be more clues. Also, any relevant errors in /opt/rockstor/var/log/rockstor.log will also help us debug more.
Btw, the refresh icon in the center is misleading and is going away in the next update. In your case, I don’t think it has anything to do with scheduled tasks being loaded.
There’s an open issue for the clone problem that i am working on currently. The fix in 3.8-4 only applies to scheduled tasks feature.