Onlyoffice .ods docs lose cell info

NextCloud 18.0.0
OnlyOffice community server 0.1.5
OnlyOffice app 4.1.4

Saving a spreadsheet in .xlsx format works as expected - data, formula and formatting are all preserved.

Saving the same spreadsheet in .ods does not work as expected. Upon re-opening the file much of the in-cell formula have been trashed as well as some cell formatting. Seems quite random what gets trashed.

Any ideas ?