There are a few reasons that your classes' conference recordings have not shown up, or are not able to be played.
First, please look in your conference recordings and try to see if you are able to play the recording or if the play button is not available. As shown in these pictures.
If the play button is accessible but the recording is not being played then it may just come down to a network or web error.
If you cannot access the play button to the recording it may be due to your teachers settings or a web error, contact your teacher for further information.
If you can not locate your recording at all it may not be published yet and you should contact your teacher for further instruction.
For any more questions regarding your class recordings and any issues that are non-network related it is best to contact your teacher for further information.