In KiCad version 8 and lower I had no problem creating Group bus labels.
simply create a label and start typing… e.g. GRP{blah blah}
.
In KiCad 9, if I create a new label with ‘L’, and select the ‘multiple label input’ ( I have no idea what this means, it wasn’t in KiCad 8) it does not do anything strange when I hit the spacebar and I can create a bus label.
But if I then go back in to edit a bus label the checkbox is missing and I can’t use the spacebar without the drop down appearing.
The bus documentation does not appear to have changed.
KiCad 9.0.3