Why is Captivate 9 only importing PPT and not PPTX?

Hello,

Have used Captivate 9 to import PPTX files without issue. Today I continue receiving a message that states "Unable to import Microsoft PowerPoint presentation. The file may be damaged." even with a brand new test PPTX. Captivate 9 does appear to bring in PPT files, not PPTX. Is this an issue with Captivate or my version of PowerPoint? 

Many thanks!

Eileen