Tracking Field History or Record Update While Offline
Often business reporting requires a record of when something occurred in Salesforce. Examples include when a service technician arrives at a client visit, when a repair or work order line item was completed, when a work order was completed, when a contract was signed, or an approval time.
How Field History Tracking Works When Online
You can select fields to track and display the field history in the History related list of an object. Field history tracking is enabled at the object level of custom objects and standard objects. Modification of your fields adds an entry to the History related list. Each entry includes the date, time, the type of change, and who made the change. This data is recorded and sent to Salesforce right away if you are online.
For a list of standard objects and more information about tracking field history, refer to Salesforce Help - Field History Tracking.
For instructions on enabling Field History Tracking, refer to Field History Tracking for Standard Objects or Field History Tracking for Custom Objects.
Offline Scenario
If you are offline, the timestamp recorded in the History related list is the time that the change is registered to Salesforce (ie. the sync time). This means that your Field History Tracking is showing the sync time and not the actual time that the change occurred in Pulsar. And this behavior is not unique to Pulsar. This is a classic offline problem since the Salesforce platform only knows about the change you made when you actually sync the data. This is the same case with SF and SFS mobile. You can check SFS documentation and their recommendations: Salesforce Help - Offline Considerations in the Field Service Mobile App. Also, below is an example of Field History on the Status field of a Service Appointment that was changed offline on SFS mobile app and then synced to Salesforce. You will see that the actual time the appointment was synced to Salesforce was registered as the tracking time.
How to Implement Field History Tracking While Offline
Fortunately, there is a work-around solution if you are offline and want Salesforce to record an accurate time that fields changed. You can create additional fields in the record and setup Pulsar to track the actual times in those fields as opposed to the standard platform fields like the LastModifiedDate or rely on Field History Tracking. You could also create a custom object mimicking the history tracking and make it a related object, so you can capture this information accurately.