Which sensors are the ones you are referencing? What are the names of them in your device list?
Typically this would suggest signaling issues at the sensor, but if multiple sensors just started showing this symptom at one time, it is more likely a problem near or with the panel.
The first thing I would try is a reboot of the panel. Settings > Advanced Settings > Reboot Panel.
Second, there is actually a newer firmware that was just released which addresses a few separate issues that arose in 2.7.0. Try updating to 2.7.2 per the steps below. Any change?