Scale is broken – when you type in the format (n, m) you get invalid string.
There’s more to this bug than I can be bothered writing up because my brain hurts.
Severity – critical.
I just tested it. Are you doing something different than I am?
Scaling by factor Dave and not necessarily in a scaled group.
Previously – I’m certain but my memory could be wrong (being a beta tester I find that I’m lost in a nether world of continuous deployment of past, present and future 
) – we could type a factor, say 2, 3 and it would work
Paul, just a quick check, are you using a corner grip to do the initial scale? If not, then that would be your issue - you can only specify a single dimension if you scale from a side grip.
Adam
So I have attempted to escape the nether world and indeed it is as you state Adam.
What I was doing was not using the scale tool, I had the object selected and used the old scale method (but that is not actually relevant as both scale methods are essentiality the same it seems) – even now muscle memory has not developed sufficiently and…
I am continually using the new move and scale changes with the old move/scale action interchangeably – one moment I’ll use the scale tool the next I’ll have an object selected and grab a scale handle.
So with the object selected I grabbed the top scale handle, kept shift down and scaled, typed 2,2 and got invalid string – the VCB shows the two scale variables changing as you drag the scale handle.
Of course grabbing the corner scale handle with the object selected typing a two variable scale factor works as expected.
If I am going to be pedantic about this – if the VCB is showing the two scale variables changing as you use a side scale handle – the expected behaviour should be to scale to the two factors that you have typed and not to have invalid string.
And if the current behaviour is the desired and intended behaviour then if you grab a side scale handle then uniform scale should not be indicated as available.