See attached BXML file and screenshot
A workaround is to make the 'filler' Component non-visible, whether it is an actual TablePane.Filler or something else.
(A non-visible Label works exactly the same as a TablePane.Filler instance)
Perhaps TablePane.Filler should default to being non-visible to avoid this problem?
I haven't investigated this in any way, so making the change may well have ramifications elsewhere.