Zoom chat function

[Maudsley]

Hi there, I was recently moderating on a course via Zoom, we had around 35 participants and all functions appeared to be running smoothly. 

One participant who hadn't engaged through the day, stated that his chat function was not working. The faculty and myself sent messages through the day with no replies, after several hours I received a chat message from the participants stating that his messages weren't sending through, is this a complication that has happened before? Is it something that can be looked into? The course was very important, he sent me a screenshot of the non-received messages, is there a way of clarifying the non-delivery of these messages? 

Many thanks, 

Aysh