You may want to enable the automatic check if you selected also the caption frame when dropping an image onto a page.

This will display a message box if you drop an image on a placeholder, but the caption frame is not selected. The purpose is to ensure that the caption text gets automatically copied from the wire or editorial image onto a caption frame - but of course, in order for that to work, a caption frame must exist and must be selected.

On the General subtab of the Extra tab on the Preferences dialog box, tick Check if the caption frame is selected when dropping an image.

Recommended: ticked.

Notes

•This functionality uses the variable F_CheckCaptFrameSel.