nanobar | No jQuery

I'm working on an application designed to create a presentation based on screenshots created with selenium webdriver. Technology stack: Python 3.8.6, Flask 1.1.2, Celery 4.4.7, Redis server 4.0.9 Ubuntu 18.04.3 LTS . When I add only one task the Celery worker works fine, but when i try to call 2 or 3 tasks one after another the tasks are received but never executed. The time of adding the task also affects the worker's behavior. When I add one task - waiting about ~ 2 seconds and then add second - all task are executed fine. But when i Try to add 3 tasks - always have problem. Sometimes first task is executed but others no but sometimes none of them are executed. This is sample of my code:

I'm running task by $.ajax - post: