ExportToolkit + ProcessManager process never finishes

Pimcore 6.8.4

Using:

Issue:
my process seems to be stuck in status running:

although the info box says that all processes have finished:

I guess the configured download button is missing because of that.

The process configuration looks like this:

running the export via shell seems to work fine and results in exit code 0

$ docker-compose exec -u www-data -w /var/www/html php bin/console export-toolkit:export --config-name="orders"

[2020-11-18 10:39:11] app.NOTICE:
[2020-11-18 10:39:11] app.INFO: export-toolkit-orders
[2020-11-18 10:39:11] app.NOTICE: Setting up export orders
[2020-11-18 10:39:11] app.NOTICE: Starting Exporting Data
[2020-11-18 10:39:12] app.NOTICE: Processing CoreShopOrder 1 from 1 (0 remaining)
[2020-11-18 10:39:12] app.DEBUG: Updating object 11997
[2020-11-18 10:39:13] app.INFO: Process Export orders, finished page: 1
[2020-11-18 10:39:13] app.NOTICE: Processing Items 1 from 1 (0 remaining)
[2020-11-18 10:39:13] app.INFO: Process Export orders, finished page: 2
[2020-11-18 10:39:13] app.NOTICE: Committing Data
committed%

$ echo $?
0