Some Bootstrap .map files missing

In a Dreamweaver project browser shows in developer mode some missing bootstrap .map files:
- bootstrap.css.map

- popper.min.js.map

- bootstrap.js.map

=> see screenshot.

Dreamweaver is up to date, and all files of the web project are transferred to the webserver.

I also tried to copy the relevant files from the official bootstrap source, but this doesn't completely fix the problem.

Thank you for your help in advance!

Stefan