This can be caused when navigating between URLs that are in different security zones. When this happens, IE replaces the tab process, which causes LeanFT to lose ''attachment'' to the tab.
There are several ways to fix this, as per HPE [KM02540656].
1. Make sure that all the web sites that are in the test are in the same security zone. This includes the home address and about:blank. To change a site security zone, open internet Options -> Security tab The zone for the current site is highlighted. Click sites and add sites as needed.
2. Disable Protected Mode for all security zones or enable Protected Mode for all sucurity zones.
3. Disable UAC on the machine. This will disable protected mode.
4. Use BrowserFactory.Attach to get a new browser test object that works with the new tab process.
I have found the easiest way to overcome this without having to modify any scripts is to check the Protected Mode box in Internet Options for all zones. This maintains security and doesn't require code changes.