When a larger transformation is performed (e.g. today I observed a user who used a CSV file of 4MB), the third step ('transform') takes somewhat long (e.g. 10 or 20 seconds). While this transformation runs in the background, a grey rectangle is shown. A user may interpret this rectangle as a bug, especially after a couple of seconds some users may be tempted to click on the "Previous" button.
Expected
A message to be shown to the user during the transformation phase that indicates that the transformation may take a couple of seconds. Such a message will make the process more understandable to users, and users that would otherwise doubt whether the transformation is still running are given feedback that the transformation is indeed running.
Observed
When a larger transformation is performed (e.g. today I observed a user who used a CSV file of 4MB), the third step ('transform') takes somewhat long (e.g. 10 or 20 seconds). While this transformation runs in the background, a grey rectangle is shown. A user may interpret this rectangle as a bug, especially after a couple of seconds some users may be tempted to click on the "Previous" button.
Expected
A message to be shown to the user during the transformation phase that indicates that the transformation may take a couple of seconds. Such a message will make the process more understandable to users, and users that would otherwise doubt whether the transformation is still running are given feedback that the transformation is indeed running.