With 22.4 the support for OSP scanners (not meaning ospd-openvas) and GMP scanners/sensors has been removed. Only these two scanner types could be created via the UI. Therefore the “New Scanner” dialog isn’t available anymore.
The enterprise version has a terminal UI for administration purposes. For adding sensors (remote scanners) it was always required to add the scanner via this terminal UI. We just removed legacy code paths in the UI.