brundlefly is correct about this. I would venture to say it's been this way since Sonar (2000ish) or earlier. It shouldn't be this way. But once you know why Delete Hole is grayed out it's easy to work around no data present. Just copy any audio into the hole and you then can delete the hole.

Kev999

brundlefly

Kev999
I'm not experiencing any problems with deleting hole and I'm using X2a, so I presume that it's a new bug that needs to be reported.

Definitely not new, and not really a bug. Here's a thread from 2005...

I deleted some empty space in a project a few days ago.  There were no audio clips, midi clips or envelope nodes in the section that I selected.  It deleted ok.
...I can check it out again...

 
OK I tried it again with the same project and it worked. But then I created a new project, added some data, selected a blank section of the timeline and clicked on the Edit menu. The Delete option was greyed out. Adding more tracks, softsynths and clips didn't help. Only after adding an automation lane, the delete option appeared. After that it worked (and delete hole worked). Then I tried removing the track with the automation and the delete option became unavailable again.

So it appears that the presence of track automation makes a difference, even if the automation consists of nothing but a horizontal line.

It threw me at first, and it does seem to have been around for a long time.
 
Once you know about it, it's not really a hardship to add a MIDI note or paste some audio first.
 
I remember when it was a lot more work involving razor blades.   Pasting a clip seems relatively insignificant compared to that nightmare. I love digital audio.

Ah yes, a perspective check
 
Sometimes when I get upset about something with my DAW I have to remind myself of what it used to take to do what I'm doing (if it was doable at all!)
We live in good times to be sure.