There is a bug in QUBEdocs Local version 4.3.1894 whereby changes to connections are not saving. There is no error message that appears so it is not immediately obvious that the changes are not being applied. This appears to only be affecting upgraded versions of the product (i.e. this version being installed as an upgrade to an existing installation as opposed to it being a brand new installation of QUBEdocs).
This error is caused by missing configuration in the latest build of the application.
Update QUBEdocs Local to the newest installer (version 4.3.1954 or later) which is available here.
We have found that creating a new connection enables changes to existing connections to be saved.