NC 18.0.3 Onlyoffice - can't edit xls files anymore. xlsx still works


strangewise after upgrading the cloud to 18.0.3. I can’t edit *.xls files anymore. It opens automatically the onlyoffice viewer, instead of the onlyoffice editor.
*.xlsx files are opening just fine.
So my workaround now is to rename the files.
Has anyone an idea?

Thank you very much