The split operator makes a new attribute, but I can't actually access or use it

I am trying to use the Split operator to split the values of an attribute (Departure_Time). This attribute stores time values in the format: hh:mm

Of this time attribute, I need only the hours, not the minutes. So if the value is 21:55, I only need the 21. The data type of the attribute is polynominal.

When I use the Split operator (with split pattern : ([0-9][0-9]) ), it does create a new attribute, called Departure_Time_1. This new attribute replaces the old attribute. This is however only visible in the metadata of the Split operator. When I run the process directly the new attribute is not visible in the result tab (only the old attribute). Also, when I link another operator to the Split operator (for example Parse Numbers, Generate Attributes or Select Attributes), I can select the new attribute (the old attribute is gone), but when I run the process it gives the error that the attribute does not exist.

So my question is, where does the new attribute get stored after using the Split operator? And how can I access this new attribute?

I just downloaded RapidMiner a few days ago for a class assignment so I have the newest version. Also I have no experience with Java whatsoever.