Looks like 2.3_264 does not work on Yosemite DP5. The app consistently does not respond to the keyboard shortcut.
I normally use the default shortcut (option-space) but tried changing it to ctrl-opt-cmd-space to see if the default shortcut was getting intercepted. No dice. Also removed and reinstalled Alfred ... to no effect.
I did not realize how dependent I have become on Alfred ... all my Macs, all the Macs I use & support at work, and all my clients Macs have it... now I am lost on m own machine!
Let me know if there's any info I can provide...