Was having same problem. Did all the steps above (Implse Cleaner and reinstall, etc.), checked beta, etc. Now not getting the update notice.
New version Impulse: v 3.27.534
Is this the latest? Are there updates for it?
How about (as I've asked for numerous times) a spreadsheet (UPDATED) with all current versions and latest update (version) numbers for all the software?
Why isn't SD doing this so we can figure out if something is or isn't working?