InDesign version: 21.5.1 x64
Operating system: Windows 11

Steps to reproduce

Open an InDesign Book containing many documents — in my case, approximately 80.
Select all documents in the Book panel in order to export the complete book to PDF.
After the export is finished, double-click one particular document in the Book panel because you want to open only that document.
InDesign begins opening every document that remained selected after the PDF export.

Expected result

Double-clicking a particular document should open only the document that was double-clicked.

If opening every selected document is considered intentional behaviour, InDesign should at least:

warn the user that a large number of documents are about to be opened;
ask for confirmation;
provide a clear way to cancel the entire operation after it has started.

Actual result

InDesign starts opening every previously selected document without warning or confirmation. There is no practical way to cancel the overall operation.

In my case, every document also displays a modal dialog asking whether the document’s hyphenation exceptions or the current user-dictionary settings should be used. However, this dialog is not a cancellation mechanism: both Yes and No continue opening the documents, and there is no Cancel button for the overall operation. The only apparent way to stop the process is to force-terminate InDesign.

Paradoxically, without these dictionary-conflict dialogs, InDesign would silently open all approximately 80 documents without asking anything at all.

Force-terminating InDesign can make the situation considerably worse. On the next launch, InDesign may attempt to recover or reopen the large number of documents that were open when the application was terminated. The application can therefore become trapped in another long and effectively uncontrollable sequence during startup. Restarting InDesign no longer provides an obvious way out.

An experienced user may know that deleting or moving the contents of the InDesign Recovery folder can interrupt this cycle. An ordinary user cannot reasonably be expected to know where this hidden recovery data is stored or that it must be removed manually. From the user’s perspective, InDesign may appear permanently broken, leaving reinstallation as the only apparent remedy.

The retained multiple selection is particularly easy to overlook because the row that was double-clicked is highlighted differently from the other selected rows. A user can therefore reasonably believe that the double-click applies only to that document.

I use and pay for Adobe InDesign on behalf of the Szent Jeromos Katolikus Bibliatársulat (St Jerome Catholic Bible Society) for professional Bible publishing. This occurred immediately after successfully generating the complete PDF of a 1,504-page Bible. A professional publishing application should not allow one accidental double-click to launch an application-blocking operation involving approximately 80 documents, offer no usable cancellation mechanism, and then potentially prevent the application from starting normally after forced termination.