Problem with adding a variable

We are unable to add variable beyond 26. Unable to see the “Add” button to add further variables.
Please help

Which version of RPA Express are you using?
We used to have this bug in 1.2.0, but it was fixed in later versions Is there any way to stop Action Flow tree expanding when a variable changes

yes, we are using 1.2.0

You should update to 1.3.0, this bug is fixed i the new version.