When it gets stuck the chat is unusable because you can’t edit your prompt because it’s generating and you can’t stop it by clicking the square stop icon.
Reloading the page doesn’t help, logging out and back in doesn’t help, clearing the cache doesn’t help.
ChatGPT often generates empty content for me too, but in my case it is enough to click on the little refresh button (which I have circled in red in the picture) a couple of times to generate the reply. This does not detract from the fact that in a conversation this error happens several times.