Iterations do not correspond to those specified in executor "ramping-arrival-rate"

Good morning,

I’m running a test on grafana k6 0.46.0 with the “ramping-arrival-rate” executor.

Each iteration only makes one http get call, so according to my definition it should launch a total of 29 iterations.

  ramping_arrival_rate_video1: {
    executor: 'ramping-arrival-rate',
    startRate: 0,
    timeUnit: '1m',
    preAllocatedVUs: 20, 
    stages: [
      { target: 2, duration: '0s' }, 
      { target: 2, duration: '1m' },
      { target: 9, duration: '0s' },
      { target: 9, duration: '3m' }
    ],    
    exec: 'scenario1'
  },

However, when I finish my test I see only 28 iterations and 29 iterations should have been done.

dockertools-k6-1                          |      █ teardown
dockertools-k6-1                          | 
dockertools-k6-1                          |    ✗ checks.........................: 96.55% ✓ 56     ✗ 2 
dockertools-k6-1                          |      data_received..................: 117 kB 484 B/s
dockertools-k6-1                          |      data_sent......................: 30 kB  125 B/s
dockertools-k6-1                          |      group_duration.................: avg=2.95s    min=353.15ms  med=604.38ms max=30.23s   p(90)=5.29s    p(95)=18.94s  
dockertools-k6-1                          |      http_req_blocked...............: avg=252.44ms min=23.45µs  med=151.07ms max=2.2s     p(90)=164.56ms p(95)=1.37s   
dockertools-k6-1                          |      http_req_connecting............: avg=42.24ms  min=0s        med=58.8ms   max=64.81ms  p(90)=63.25ms  p(95)=63.39ms 
dockertools-k6-1                          |      http_req_duration..............: avg=2.66s    min=35.61ms   med=440.65ms max=30.06s   p(90)=5.06s    p(95)=17.93s  
dockertools-k6-1                          |        { expected_response:true }...: avg=1.69s    min=35.61ms   med=439.9ms  max=25.93s   p(90)=1.96s    p(95)=5.55s   
dockertools-k6-1                          |      ✓ { status:"200" }.............: avg=1.69s    min=35.61ms   med=439.9ms  max=25.93s   p(90)=1.96s    p(95)=5.55s   
dockertools-k6-1                          |      ✓ { status:"202" }.............: avg=0s       min=0s        med=0s       max=0s       p(90)=0s       p(95)=0s      
dockertools-k6-1                          |    ✓ http_req_failed................: 3.44%  ✓ 1      ✗ 28
dockertools-k6-1                          |      http_req_receiving.............: avg=3.64ms   min=1.47ms    med=3.13ms   max=16.01ms  p(90)=4.54ms   p(95)=5.39ms  
dockertools-k6-1                          |      http_req_sending...............: avg=1.5ms    min=704.41µs med=1.41ms   max=4.63ms   p(90)=1.81ms   p(95)=2.12ms  
dockertools-k6-1                          |      http_req_tls_handshaking.......: avg=68.81ms  min=0s        med=89.71ms  max=155.64ms p(90)=97.15ms  p(95)=101.75ms
dockertools-k6-1                          |      http_req_waiting...............: avg=2.66s    min=31.91ms   med=437.01ms max=30.05s   p(90)=5.06s    p(95)=17.93s  
dockertools-k6-1                          |      http_reqs......................: 29     0.119687/s
dockertools-k6-1                          |      iteration_duration.............: avg=2.83s    min=290.37µs med=606.75ms max=30.23s   p(90)=5.1s     p(95)=16.94s  
dockertools-k6-1                          |      iterations.....................: 28     0.11556/s
dockertools-k6-1                          |      vus............................: 0      min=0      max=2 
dockertools-k6-1                          |      vus_max........................: 20     min=20     max=20
dockertools-k6-1                          | running (4m02.3s), 00/20 VUs, 28 complete and 0 interrupted iterations
dockertools-k6-1                          | ramping_arrival_rate_video1 ✓ [ 100% ] 00/20 VUs  4m0s  0.15 iters/s
dockertools-k6-1                          | time="2024-01-19T08:38:17Z" level=error msg="thresholds on metrics 'checks' have been crossed"

Why are the iterations that I have indicated not carried out?

If I configure the executor as follows, the specified iterations are performed (29 iterations)

  ramping_arrival_rate_video1: {
    executor: 'ramping-arrival-rate',
    startRate: 0,
    timeUnit: '1m',
    preAllocatedVUs: 20, 
    stages: [
      { target: 2, duration: '0s' }, 
      { target: 2, duration: '61s' },
      { target: 9, duration: '0s' },
      { target: 9, duration: '3m' }
    ],    
    exec: 'scenario1'
  },

Thanks