one-time write to the mode, then all works. However, if no such write
is done, the variable always remains zero. I have used the memory
debugger as well as shuffled the code around and used guard variables
nothing changed. The problem always moved with the changes I did. So
I now consider the one-time write a usable work-around, because it
definitely fixes the issue even though it does not explain why it
happens.
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