I have the same issue (Cubase 11.0.41). It also applies when you want to import the folder and it’s containing audio tracks WITH the audio events. Normal behaviour (as it is written in the manual) should be the creation of a new track version with the new audio on it. Instead, you get a new track version without the audio, just empty tracks. This does not happen if you import the audio tracks individually.
But there is more: try to import an audio track with audio events that contain audio warp and vari audio editing on it. The audio warp data gets importet, the vari audio data gets lost. This happens of course only if you import the audio tracks individually. When you try to import a whole folder with the audio events (that contain the audio warp and vari audio data) you will get empty tracks like described above.
But this seems to be not a new thing in Cubase, there is an old thread from a year ago that descirbes the same behaviour (loosing the vari audio data when importing tracks with audio events that contains vari audio data).
Thread: VariAudio lost after track archive import on different PC - #2 by Tomess