Sound mix on the two interpretation channels

We are very regular users of Language interpretation on Zoom, main channel is English and we have Chinese and Cantonese Interpretation. 

In a meeting last week, the sounds were mixed on two interpretion channels Chinese and Cantonese, that the participants heard two voices of Chinese and Cantonese. This issue happened after the 15 minutes of the meeting, while at the beginning everything was okay. Then I updated the interpretors' role, it resume to normal. 

Does anyone have the same issue before and what is the problem, and how to avoid this issue please?