PDF files in prework module do not show Japanese fonts

Hi all,

I am making a multi lingual course for Japanese which inculde Chinese translation textbook, but the uploaded pdf textbook do not show Japanese fonts at all, as the figs show below.

The left panel shows Japanese well as a single file, but the right panel shows the Japanese fonts missing in Captivate Prime as marked by yellow highlighter.

But in other case, in the English translation version textbook, the Japanese fonts work well.

I am be grateful for any recommendations!