You can check the Data merge panel flyout menu for "Content placement option"
There you can choose the appropriate settings to get the image placed properly in the placeholders.
I choose "Fit images propotinally" with "Centre the images" option unchecked to get the images snapped to the top of the placeholders frame.
My fix was:
Object/Fitting/Frame Fitting Options/Align From (top of Transform grid)
The Placeholder behavior needed to be set.
Great , thanks for the update.
The option you used is specific to the placeholder/frame settings hence if you create another frame then you need to the change the settings for the same as well.
The option in data merge panel will help to specify the default settings for the current document or for all future data merge projects.