Had (seemingly) intermittent no start, rapid flashing anti-theft light. After a lot of searching for solutions with no luck I finally found the cause.
I have a wireless QI cellphone charger mounted on the dash very close to ignition switch. When my phone is charging through this it must be causing interference preventing the chip in the key from being read properly , if I remove the phone then all is fine.
Haven't found any mention of this possible cause of PATS no start problem so hopefully this post might just help someone out