Option-Esc doesn't start Text To Speech

This happened a few times before but it usually took a few weeks or months to reappear.

When I hit the defaul "Option-Esc" which starts the Text-To-Speech engine for selected text, it does nothing. Normally hitting this key combination once starts it, hitting it again terminates the reading. Now I have to start it manually by right-clicking and going to "Voice" and then "Begin reading", but the key combination still works for terminating the reading.

When I restart, it goes back to working, but then something changes and it stops working. I've closed all programs but Chrome (and then again, leaving only Safari) but this makes no difference.

Finally, I've checked the logs in the Console to see if there were any entries regarding this problem and nothing pops up. I've searched for this online, but I can't find anything since when I search for "option-esc" things with "Command-option-esc" come up which are far too numerous.