Tabindex and dynamic controls : not following?

I have an MacOS application where all the input fields are dynamically generated at runtime. Now I rebuilt it with Xojo 2018r4 and only now I notice that the taborder, which in the past followed the tabindex property, seems no longer to work.

I added two comboboxes to the input screen and reordered the tabindexes of the fields. I can tab in the ancient order until I come to the new fields, then it tabs into the first field after the new ones and only at the end the focus goes to the new fields. I tried to influence the tab-order by setting the order in which these fields are generated, but this does not work as well.

I don’t get how the taborder for dynamically generated controls is now working. Something changed here in comparison to older versions of Xojo.

Does anyone noticed this or knows more about it?

I missed to adjust the tabindex of a container control and this was the cause of the erratic behavior of my app.