Hello,
If you don’t mind, I will join this thread as well.
The DocSpace is out-of-the-box portal solution where the Document server is already integrated. This is why the described situation seems unusual.
Is it possible to run a test? Please run a completely fresh installations without your changes in the installation script (also, we’ve released Document server v.9.3. Please download fresh installation script).
Will the situation with the lack of Document server integration reproduce?
If so, please collect entire DocSpace logs folder (/var/lib/docker/volumes/onlyoffice_log_data/_data)and make a screenshot of the Document service integration page while clicking ‘Save’ button.