If I understand what you are referring to...then when you get a miniture screen, set it up in the top-left of your monitor...then grab the bottom right of the window, and drag it toward the bottom right of your monitor. That will manually expand it to full size.
Next, open a new window. Your window should now be full size like it is supposed to be.
I have that happen alot, if I minimize a screen, then close out prematurely before restoring it to full-size.
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