Impossible to open office document from NextCloud Hub file list

Dear all,
I installed NextCloud runing in a docker container runing on my OMV6 NAS.
Everyting seems to work well. I did install through the NextCloud GUI the recommended collaboration applications (Office etc…°). I can open pdf files for example. However, when trying to open any office documents, I face a blank screen like the one attached telling that the system loads the document and nothing else happen after…
Would you have an idea of what is wrong ?
Thank you very much in advance,
Best regards,