This is happening all the time in preview mode in Mendix Studio. It seems to happen if I am dormant for more than a few seconds (meaning not clicking around) when I’m making notes in the buzz for bugs etc. I have to refresh the screen, it then brings me back to development and then I have to hit preview again to start over. Is there a fix for this? or known issue?
If this happens in Mendix Studio, then this is likely an issue that Mendix has to fix. But first find out if this is application related. Does this occur in any other of your applications? Is this in version 9.0.5? Is yours a free or a paid application?
If you can reproduce this behavior in a second app, then my advise is to ask Mendix to have a look. See support.mendix.com.
If not, then some part of your app is causing this.