Chat tool does not display user in user list in chat when on iPhone (iPad as well?)

This issue is most easily replicated on Apple products. On Master, the Admin creates two users and add the Chat tool to a site. The Admin continues on the desktop Chrome browser to write random messages in chat. Send the link to the chat room to the first of your two mobile "testers"  1st User: iPhone6s , clicks on link and Safari opens  2nd User: Android 7.0 (kernel 3.10.6.1) (Samsung GalaxyNote 5) Users login (as one of the users created in step 1), and  are redirected to the Chat Room. Both users type text messages in the Chat window. Expected Behavior:  "Users in Chat Room" lists full complement of those in chat room. Messages are received in the order they are input. To Now Replicate the Bug: The iPhone user opens another app on their phone, then returns to the Safari chat window. OR iPhone user's phone locks and they come back to the open Chat session from there. from their logged in Sakai session and is removed from the Chat users display.  The Bug: By one or the other of these methods, the Chat Room user's name is removed from the list of those active in the Chat room and never added back, unless they exit the Chat Room and re-enter.  The Users coincidentally, are also removed from the Site Portal's list of active site members.