EX2 Ultra racing fan condition

Recently, when leaving my NAS connected overnight (normal operations), I find the fan in an obvious racing condition in the morning which is a relatively new occurrence. The NAS is well ventilated and not experiencing noticeable excessive heat issues overnight or during the day. The issue is generally resolved by rebooting the NAS but I shouldn’t have to reboot every morning and this is a new issue. I do have the latest firmware update and the racing condition started to occur after the latest firmware update was applied. Any suggestions would be appreciated.