We use the REST API projection ProjectNavigator to integrate project activities to our Project Management Tool. We use a simple GET to fetch all activites. If we send a request and get 900 records, we might get 800 records a minute later. The 100 missing records is then back again in the next call, but we might lack 50 others. There seems to be no logic in which records are missing, some of them not altered in years. 

We use the standard projection ProjectNavigator/Activities. 

Any thoughts?