Athena AS P4000 Sub issue

I have the AS P4000 hooked to a Yamaha 5850 receiver. My set up is at least 8yrs old. It has worked fine for many years to my knowledge. Yesterday I noticed something -


For some reason the sub wont utilize the "auto" feature, which is a toggle switch on the rear of the sub. If i turn the sub ON it works great. But if left in "auto" mode it wont turn itself on when something is sending low frequency. And after a minute or two it will turn itself back off if I toggle between "auto" and "ON". My surround settings are set to "small" and the crossover is set to 100mhz.



Any ideas what I can do to get the sub to automatically come on? Like it should and used to do...