Nextcloud cannot save any change in ods file with chart

I managed to install nextcloud with collabora. Normally it works fine.

But, it is not possible to save the file in a special case.

I created a simple chart in libreoffice calc as an .ods file and uploaded to nextcloud. If I open this file and change any cell (even outside the data series), it is not possible to save it. Nextcloud complains about permissions.

This happens only with ods having a chart. ods files without chart don’t exhibit this problem. xlsx with chart has no problem as well.

I would appreciate any hint. Thanks.

I have seen that nobody participates in these forums. Something similar happens to me.