In our custom ECL extension, we ran into the following problem. We created an ECL extension that allowed us to browse folders and files in an external system.
The folders and subfolders are showing up fine, and files can also be opened correctly. However, we did notice that the files were also appearing in the tree in the Content Manager Explorer, and were also expandable.
When expanding these items, strangely enough, we would see a list of our publications (see screenshot).
Our ECL extension was based on one of the example implementations we found, but t here, this problem would not occur.