Am I not doing it right?

Possibly. It was working for me yesterday.

1. Describe the specific steps you took, the result you expected, and the result that actually happened.
2. Describe your OS (your computer's Operating System: Mac/Windows/Linux/etc. & version).
3. Describe if Inkscape was newly installed, or upgraded from an earlier version.
4. Describe the version of Inkscape and the installer you used (the file you downloaded from the website: .msi/.exe/.zip/other ). 
5. Describe any special hardware being used, like tablet/stylus or multiple monitors.
6. Describe any helper/assistive programs or keyboard modifiers (macros, languages, etc.).

Bonus points, if you:

• Attach* a screenshot of the issue.
• Attach* an example SVG file that has the issue.

I apologize for the little information, by mistake I pressed the send button....

I am attaching a video and the sample file.

The two objects selected are circles, as described in the status bar. I'd use Path>Object to path before using the interpolate extension.

I can't..... I'm trying to reproduce this, minute 9 :  link

I also tried with Inkscape 1.2.2 for win 7/64bit

Maybe this:

I succeeded, thanks for your involvement and help.

I don't think you can see the attached videos, can you confirm?

Edited by moderator to change attachment type. Clicking on the attachment link can play the file in the browser.

Just an image as a placeholder for a video visible.

How do I attach video?

L.E.

I noticed that it was edited by the moderator, clicking on the attachment link can play the file in the browser.