We're in a transition phase right now. Due to the recent activity by Hertz and DTAG, our automated systems are only capable of handling the companies that still partner with us. We are having to handle "tracked" reservations booked with other companies a bit more manually for now while we work on building a new system that will support rentals with all companies.
While we work through this, you may encounter some glitches, and it's probably best to consider AutoSlash as an "assistant" in helping you find the best rate rather than the be-all-end-all solution. (Our aim is to eventually be that solution so that you don't have to do any work at all!)
For "tracked" reservations (ones you've booked elsewhere but have submitted for tracking), I'll make a few notes about what we are currently doing so you can best adapt your use of that function:
-We try but are a long way from 100% at being able to factor in any membership affiliations you included on your original "tracked" reservation
-We prioritize our offers based on an admittedly-subjective ranking of the rental companies. Generally, if you had booked with Hertz, you wouldn't get offered a lower rate with Enterprise, but you would if we found a lower rate with National or Avis. If you had booked with Payless, we'd send you the cheapest rate from any other company.

-Once we send you an email alerting you of a lower price, we don't really have a way of knowing whether you took advantage of it, so our current practice is to not send any further emails. Thus, if you want to continue tracking for further price drops after you rebook, you'll need to submit another tracking request for your new confirmation details and new price.
It's far from a perfect system, but it at least allows us to provide some type of service while we work towards a new, more comprehensive service where we hope to provide all of the features that FTers want.