Nortton Family Android Time limit not working

Have installed norton family app on two devices, one with Android 6 and the other with android 4.4.

The time limit for all devices has been set to 3 hours.

When using the devices, the time limit does reduce as expected, but then sometimes jumps back up almost to the full time period e.g. 2 hours and 58 minutes. A full day's use therefore does not use more than the 3 hours allocated.

(1) I need a solution to this problem. The time limits need to be more accurate (no resets).

(2) I would like to suggest a feature: It would be useful to set a single time limit shared for all devices, i.e. 3 hours altogether, whichever device is used.