I don't think I have seen a bug in the module as such. Consider the following quote from the documentation:

A number of rows and/or columns can be marked as 'fixed' - and so can serve as 'headings' for the remainder the rows which are scrollable.

and also:

Entries in the Table are simply ordinary perl/Tk widgets. They should be created with the Table as their parent.

Your sample code ignored the second instruction. That is not a bug in the module; it is a bug in your code. Having fixed that the scroll bar was correctly generated over the only column that was not fixed. That column is very narrow: so also therefore is the scrollbar. That is not a bug either.