H&T doesn't wake up automatically (only with button)

I have 5 H&T sensors. I changed the battery to one of them and it stopped reporting data automatically (it worked before that).

If I press the button, the sensor wakes up and reports data normally one time. Then it starts showing constant light for a long while, then goes to sleep, and never reports again until I press the button again.

How do I make the sensor work normally again?

Firmware update or downgrade doesn't help, factory reset does nothing (I don't think holding the button for 10 seconds even does a factory reset, but I'm not sure.)

On a side note, the "user manual" of these H&T sensors is A FREAKING JOKE. I get all sorts of random undocumented blinking behaviours and I'm supposed to somehow figure out what they all mean? Extremely frustrating and time-consuming trying to get these to work.

Thanks for replying. But threshold values are not the problem. They are the same as before, and the sensor has not reported in days. (Unless I press the button, in which case it reports exactly once, then goes back to sleep forever.)

After changing batteries to all sensors, two more sensors are now showing the same weird behavior. They report data only when the button is pressed, never report otherwise.

1) What else can I try?

2) Are the H&T led blinking behaviors/meanings explained somewhere? (I mean explained properly, not the joke of a manual the device was sent with.)