Over the time i found some serious bugs in eagle. This bug is basically not a real bug, but result in a weird behavior.
The problem is in the board editor and in the library package editor. I found this, when I made a package for a AC to DC rectifier. For indicating the ac pads I used the character ~
Later, when i made the layout, I rotate the device. The problem is, that I used the text function to add this character to the package. The result is a that the position is then not always the same and can even lay on a pad. Sadly I changed the package already, so I can't make an example video.
I demonstrate this here:
The symbols are letter which are placed inside the package definition. They are in the tPlace layer. This example shows a rectifier.
Solution is: Make all symbols in a package with lines, never with inserted text.