Facing Inter-Task Delay while executing nested pipeline tasks

[prayaagmahajan]

I am experiencing an unexpected inter-task delay while executing a pipeline in Airflow 3.1.7.

airflow==3.1.7
apache-airflow-providers-celery==3.13.0

Pipeline Structure
- Master Pipeline (DAG)
- Contains a Nested Pipeline
- The nested pipeline contains multiple pipeline tasks
- Each pipeline task executes three SQL tasks sequentially

Issue Observed

Within one of the pipeline tasks:

• The first two SQL tasks execute successfully and complete without delay.
• The third SQL task, however, starts approximately 40–45 minutes after the second SQL task completes.

Due to this delay, the total execution time of the pipeline task becomes approximately 43 minutes, even though the actual SQL execution time is minimal.

Below is the SQL entries for the tasks.

+--------------------------------------+----------------------------+----------------------------+
| demo_task | start_date | end_date |
+--------------------------------------+----------------------------+----------------------------+
| START1 | 2026-02-18 11:03:00.572031 | 2026-02-18 11:03:05.461282 |
| SQL_TASK_1 | 2026-02-18 11:05:03.191372 | 2026-02-18 11:05:05.756707 |
| SQL_TASK_2 | 2026-02-18 11:39:30.286825 | 2026-02-18 11:39:32.576455 |
| SQL_TASK_3 | 2026-02-18 11:39:30.300086 | 2026-02-18 11:39:47.026262 |