Certain probe-specific features cause the measurement reading to lock to its current value until the probe has finished its action. One such example is probe purge, which heats up the probe's sensor to remove contamination. While the purge cycle is running, measurements are not updated.
In the case of purge, the Indigo display shows either the probe message Purge in progress or, depending on the connected probe, the high-level transmitter message Waiting for measurements.
Similarly, when the probe is initializing at start-up or has been restarted, up-to-date measurement data is not available and the Indigo display shows the message Waiting for measurements.