Some placed images don't re-size as frames are enlarged

[Rob SF]

For most of my placed images within a photo section, I'm able to resize an image by shift-dragging a corner of its frame. Occasionally, I'll have an image that doesn't enlarge but simply stays in its original position and size as I enlarge the frame. There's no difference in the file type or, as far as I can see, its dimensions. 

Please see the attached screen grab. Can someone explain what's going on, or isn't?

Many thanks.

[Old Bruce]

It will have to do with the Properties of the Picture Frame(s). Looks like the one on the right has the Properties set to "None" and the one on the Left is set to "Max Fit". Select the Picture frame with the Move tool or the Picture frame tool and hit the Properties button on the Context toolbar.

[walt.farrell]

Different scaling properties set for the Picture Frames? Check the frame properties in the Context Toolbar.

[Rob SF]

Thanks, Bruce and Walt, both. This was it.