Permission error in workflow ("error in lookup container")

Dear experts,

in a workflow I see the following error as a “Current Job Error” without any processor executed. The error points to a datatable which I am the owner of and I have full permissions on the project.

The same workflow worked before and when I open the data tables involved manually (they are “loaded by variable”, and I can open them by clicking the Link in the Data Table Load) I can see the data tables without issues (and there is no AA applied).

Can anyone give a hint what the problem could be?

EDIT: Just realized that there is a technical user between my execution and the workflow… So for my own user it is working, but for the technical user it is not. Both are in the same group with ALL PERMISSIONS, but my own user is “Domain Admin” - in contrast to the technical user.

If I change the technical user to “Domain Admin” he is also able to execute this wf. After removing domain admin, it is again not working with the error below.

Any hints welcome!