Once support for Windows 10 native notifications is released, users who choose to use Windows notifications will be able to utilize Windows OS specific settings for the length of time to display notifications. Mac does not have an OS specific setting, so will not have the support.
An error occurred while saving the commentchasila commented
I thought I was doing something wrong until I saw the comments here from many others with this problem. First, this causes a lot of pain when I don't happen to see the chat notification for the few seconds it's visible. This has to be fixed. Second, why does IOS even allow the 'persistent' option to be selected?