Perhaps try creating a totally new window definition and configuring the parameters as desired.
Once in a blue moon we see that the window definition somehow becomes corrupt.
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I created a new window but now the left placement value is imposing a limitation parameter. I am entering identical values to my window in the old X5 version of the project...all settings are identical. Any reason why this would be happening?
I finally got it to work. However, if I go in to edit ANY of the settings, it prompts me to make the necessary adjustments to the placement values and I have to cancel out of my edit. This has to be a bug in the software.