The backround sync does not work immediately

[realconvis]

I try to get the backround sync running for a PWA with this config:

workbox: {
        runtimeCaching: [
          {
            handler: "NetworkOnly",
            urlPattern: new RegExp("^https://localhost/api/basic_packages$"),
            method: "POST",
            options: {
              backgroundSync: {
                name: "postQueue",
                options: {
                  maxRetentionTime: 24 * 60,
                },
              },
            },
          },

I clear all local storages and caches and load the application in browser.
I install the application.
I select the checkbox "offline" for serviceworker in devtools of chrome.
The post requests do not end up in the queue.
But if i reload the PWA while offline, it suddenly works.
The matching requests end up in the queue like expceted.

If i use a string instead of the regexp, it works from the beginning without the reload.

What could be the problem?

[realconvis]

sorry, wrong category - i´ll post it in the right category