I just installed the 2016.12 update and I'm now seeing the 'no delete' behavior too. Also the I for inspector shortcut works when it feels like it. Strange indeed - i'll try some of the suggestions posted to see if I can sort this.    

OK I found a fix.............
 
The issue only happens for me when I have a lens selected (ie any other but 'none') and the Synth Rack is docked at the top of the browser. The delete key and I keyboard shortcut don't work.
 
If I undock the synth rack from the browser, move it to the bottom of the browser, or select 'none' as my lens, everything works as it should. In my case I had my custom lens set with the synth rack docked on top of the browser. I've just moved it to the bottom and re-saved my lens. Quirky, yes, but fixed for now. HTH.  

Bristol_Jonesey
Del key works as expected here, on audio clips, midi clips, prv notes

I put this on another post and you suggested it was because I'm from Yorkshire....
we are known to be tight fisted though lol

+1   :(
 
Think I will try a rollback to August...

Just rolled back to August, and it works again...

Glad I found this. Will delete operate normally & fixed in the next update?

For me, delete key is not working to delete clips in track view, but only if the synth rack is docked on top. Unfortunately, the synth rack is docking itself at the top when saving files and the browser is collapsed, which I have reported as CWBRN-64615.

Delete key works randomly.

Fix for me:  Re-bind Delete key in preferences and save lens.  Appears to be lens-related.  I did this and now my delete key works all the time again using my main lens.  Not sure if you'd need to do this with all lenses.

Confirmed. This happened to me and I just re-bound it in Prefs. It took me a while to figure out what the heck was going on!