Currently, we haven’t receive any reports from other users similar to your concern, simon21.

You might want to check your IMac’s control panel or your Applications folder. If it’s no longer there, you can download the new free version of the QuickBooks Online app for Mac. 

The steps on how to get the app are laid out in this article: Install the QuickBooks Online for Mac 

Aside from this, you can always access your QuickBooks account through your regular browser. Visit us again if you have other questions.