Why is the pressure not changing when I set a new value?

If the system detects a drop in pressure during measurements, a dialogue box opens to notify the user that the system has a potential leak, and a red alert appears next to the pressure reading:

The pressure can not be changed or reset until this alert has been acknowledged. To do this, the user should check that the pressure nozzle is inserted or re-inserted correctly and fully sealed, click OK on the dialogue box, then simply click on the red circle icon next to the pressure value to dismiss the alert and re-enable the APS. The APS will then return to the pressure value being applied before the potential leak was detected.