Missing "send button" in phplist


I am using phplist for 3 years and didn’t have any problems till now. A week ago I updated the version to 3.3.1.
After the update, I tried to send a campaign moving through all the steps as usual: content, format, list etc.
When I go to the last step “Finish”, there is no sending button! I see only “Place campaign in Queue for Sending” and after clicking on it - “Campaign added” and “Camaign queued”, but the queue is not processing. Please see the uploaded image. The camaign is active, but not sent, with no views, no bounces. I don’t know if something happend after the update, or maybe I am missing something else.
I hope you can help me solve this problem. Thank you in advance.