The engine is not running correctly - scaled 15 different generators and only 10 of them start
Release : SAAS
Component : PACKAGE CA BLAZEMETER
When looking at the configuration for this particular test, the Dry_Run_Guest is set to run with 1 user per engine for a 30-minute duration. The data for this specific scenario in this report shows that it is reaching a maximum of 2 concurrent users (which is the expected amount). The issue with this scenario, though, is they are using a 20-second timer at the end of each iteration, so the full test will not remain at that 2 concurrent user measure for the duration of the test (check the JMeter script from this scenario in the above report).
As for the second scenario, these engines are all spinning up, but the same 20-second timer mentioned in the first scenario is present in several places in their script, which is affecting the overall concurrency for their tests. The longer wait times are generating users that are completely inactive for a long period of time. This article (https://guide.blazemeter.com/hc/en-us/articles/360000820137-Max-Users-vs-Total-Users-Did-All-My-Users-Run-) best illustrates why they are seeing the concurrency measurement not match up with their expectations