Issue with image imported from a master file

I have one recommendation: use a real PPT plug in if this is what you need. Using Captivate as a PPT converter is not the best idea. Captivate is an eLearning authoring tool, not a HTML converter for presentations. You'll get much better results when you use the assets (like backgrounds, graphics etc) and create slides from scratch in Captivate. An alternative could be to capture the PPT presentation while it is playing with either the video demo (cpvc) in Captivate or with the classic capture (Software simulation). The first scenario will give you a good quality pure video (no interaction), the second one will allow you to add interactivity because it is slide-based.

When importing PP each PPT-slide is converted to a movie (= no control over individual objects nor animations), and the weird situation where PPT is always using print units (in or cm) for an application that is meant to be used on screens, and those have to be converted to pixels as is normal for weboutput in Captivate, causes issues.  Take out that logo, put it in Captivate on the main master slide or time it for the rest of the project. Then you'll have control over its look and size.

You don't mention the version of Captivate that you are using, nor the PPT version. Did you use High Fidelity option when importing?