How old is your stick? My stick did this at the Xmas 5 Days (recorded multiple punches at each unit) but it was because it was >5yrs old rather than sitting at a control for too long so I got a new (rebatteried) one.
Splits seem to suggest you got them all.
Its about that vintage, so you may be right. ACT has the battery test unit at all events and it responded well to that before I started. I'm thinking that SIAC requires a higher battery level than normal?
It requires a battery level, which a normal SI does not.