What has the temperatures been at?
warmer temperatures tend to give poor performance.
the sensor is looking for a temperature change in motion as in a 60 degree day trip easily as a 85 degree animal passes by but when its 85 out it only picks up night time picture when the temp drop.
I'm not saying thats whats going on with yours but I get dead spell every year as it warms. I would try setting a few in shaded areas to see if you can get back on them or find places you expect them in the early morning / late evening.
