Latest Portfolio Widget (Portfoliobox) renders wrong links

Hi enfold-team,
I have a quite strange problem with a latest portfolio widget of a wordpress-/enfold website. The portfolio widget is used in sidebars for portfolio posts to show other portfolio items of the same area.
Error description:
– 4 different portfolio widgets / sidebars are configured to display portfolio posts out of 1-9 selected categories and should display up to 20 items
– each portfolio post has one of the sidebars assigned
– most widgets work as expected but several portfolio posts have wrong urls (all urls of the widget) in the portfolio widget, e.g. https://example.com/projekte/ (this is actually the portfolio root)
– other portfolio posts with the same sidebar have correct URLs to the other posts shown in the widget

Unfortunately, I can not find any problems or errors in the debug mode or in any logs or any problems in the post itself. I can not find a schema or a hint to the error. Do you have any idea what the problem could be?
Thank you very much for any help in advance!
Christian