Guys, please do not hit me but, can it be that somehow you jump into another plane without consiously be aware of it?
Maybe you should try to hift-F2 and check whether your plane is still flying somewhere.
I am saying this because I experiened a sudden "unvolontarily entering another plane" while shifting-F2 and ctrling-F2 on one Quick Mission although I had not pressed Alt-F1.
Just in case...
~S~
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