it happens all the damm time. i know exactly what your problem is, and i still haven't quite figured this one out myself yet either. it's pretty retarded that the OS won't even give administrators access to the $files. -but then again, if we compiled everything stupid about windows, this would be just one thing in a long list of quirks, and design flaws that make absolutely no sense. many of which, development has no intention of fixing. the list is massive, and for as many flaws as the OS has, it baffles me that microsoft has the gaul to charge anyone over $$100 of ANY of their products, let alone that it's legal to sell such broken software with no intention of fixing it. there are tons of stupid flaws like this that have carried on from windows XP to the present, and plague every version of windows with no fix in sight, because dev at microsoft is so damm lazy, they won't fix or add anything that requires going to far back in history in the sourcecode. **** most of the original XP coding team is gone, which explains a lot in terms of software bloat, excessive resource demands, performance degradation do to new, slow code. i've been using windows since before windows95 when it came in 5.25FLOPPIES, and XP was the last great release. windows10 doesn't even come close. it's just 8.1 with a startbutton, which they added, because of customer backlash. windows8.x was so bad the guy responsible lost his job at microsoft if that gives you an idea of how bad it is.
it's great that microsoft gives you the option to grow and shrink partitions, and then forbids you from doing it, because of their own illogical design flaws, no access $files. horrible. no file, or operating system feature should ever be forbidden from a full on, locally logged in, administrator. administrators don't need microsoft to hold their hand. most of us know the OS better than most microsoft techsupport people. that's a fact.