I can reproduce this with Firefox 88.0.1 (64 bit) on Linux
I have tested this with Brave 1.23.75 Chromium: 90.0.4430.93 (Build oficial) (64 bits) on Linux and I can't reproduce this.
Steps to reproduce
- Go to https://en.wikipedia.org/w/index.php?title=Template:Cite_news/doc&action=edit
- Click the "Manage TemplateData" button
- Click the "Edit maps" button
- It displays a left-panel with 2 items, the first one is selected. Try to select the second one
I can select the second item, to display it's contents on the right panel
Clicking on the second item does nothing. In fact, the cursor arrow doesn't change to a hand giving feedback about a clickable element.
I can remove the item or add new maps, but I still can't select other items.
I've opened Firefox with the option "problem resolution mode" that disables all extensions, and also opened the link while logged-out.