Finally resolved!!
It seems to be an issue with word and a corrut .normal-file in the German version:
Today I had a call with Clarivate. They gave me the advice to follow the steps in the attachment to this file.
I did that and beside that I changed the language of the operating system to English - and Word worked well with Endnote.
After that, I changed the language back to German. Word announced me, that it changed the .normal-file – And the procedure between Endnote and Word crashed again.
Therefore the German Version of the .normal -file in Word seems to produce the corruption between Endnote and Word.
