Error with chunked file uploads through Windows Client

Background info:

  • Nextcloud server 20.0.11 running on Ubuntu 20.04.2 LTS
  • Nextcloud client running on Windows 21H1 build 19043.1165

I can upload files larger than 10 MB or so through the web interface but they do not sync through the Windows client. Files smaller than 10 MB sync correctly through the Windows client. I have checked the php.ini config and the limits are much more than 10 MB. I have checked permissions on the data directory and www-data is the owner of it and has permissions (and its subdirectories).

The error from my Windows client:

Server replied "403 Forbidden" to MKCOL https://[server ip]/nextcloud/remote.php/dav/uploads/user/164584880" (Could not create directory //164584880)

I recently reinstalled NextCloud after reconfiguring my server data partitions. Previously uploads larger than 10 MB worked on my NextCloud setup when using the Windows client.

What could be the issue here?