I think you are thinking of SB 1532, which failed it's first Final Read on the 27th 16-14. What did happen is a Senator aske them to vote to reconsider, and THAT [passed, so it's not dead yet...BUT the Governor stated he will not sign any more bills until the budget is finalized, which has two Republican opponents saying it is too big and they don't like the flat tax part of it. So, one of them, a lady from Flagstaff, has literally been playing hooky from work, knowing that she controls that slim majority. So, don't expect this to go through easily, with this kind of BS in the way.
Here is the link to the fact sheet - the reason it didn't show up on anyone's radar is it was subject to a Strike Everything amendment.
https://www.azleg.gov/legtext/55leg/1R/summary/S.1532ED_ASPASSEDHOUSE.pdf