I've had major problems with my scheduled tasks in 4.9 as well.  So much so, that I ended up exposing all the functionality I needed via a webservice and built a Windows service to run the scheduled task for me (obviously not the optimal solution).  Even before 4.9, however, I had major issues with the "timer" mode but the "request" mode worked fine.  Now in 4.9, they both have issues.  Rodney has made that post to the sponsor forum to sum it up already, but my issues currently are that the items fire off as many as 5-8 times all at once and essentially reprocess the same stuff over and over.  The items I'm processing are reminders for the most part, so at least it doesn't have an adverse affect on the data, but is pretty annoying to receive so many reminders of the exact same item.  It also had a lot of "thread aborting" exceptions in the scheduler process.

Anyway, would *love* to be able to identify the root of the cause and squash it.

arggh!!

I've just discovered this on my system as well. None of my tasks have been running - pesumably since I upgraded to 4.9 a while back. I can force them to run once on startup, but they won't keep going. I turned on the debug mode and it says it loads the tasks, but then the scheduler stops for no apparent reason.

My portal doesn't work in timer mode so I'm stuck with this.

what a huge pain

I have the same issue, has anybody soled it?