Unfortunately, it is too late for checking the logs... I have downgraded to 0.94.4.3 and be happy again... waiting for a new release.
The issue looks like this one:
ckvsoft
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<a rel="nofollow" target="_blank" href="https://forum.repetier.com/discussion/8372/problem-nach-update-0-94-3-auf-1-0-0-pro-version">December 27</a> </span>
<span> in <a rel="nofollow" target="_blank" href="https://forum.repetier.com/categories/repetier-server-bug-reports">Bug Reports</a></span></div></div>He described nearly the same behavior after upgrade to 1.0.0...<br/>