Bebe, the same exact thing happened to me starting yesterday morning. I also contacted support. They replied:

“Sorry you’re experiencing that. We’ve been investigating this issue and have made some changes that should make this less frequent. Can you let me know if you notice an improvement?”

I understand coding and troubleshooting a website as complex and huge as Medium must be a challenge. But this is a particularly annoying bug as a reader. And not good for the writers not getting my claps also. I hope they figure it out soon.