No it is not inverted. Inversion means that the auxiliary verb goes before the subject. e.g. Not until we had reached the top did we realise how far we had come. When a sentence begins with the phrase not until, the subject and auxiliary verb in the first clause, immediately after not until, are not inverted ("we had reached"). However, in the second clause, the subject and auxiliary verb are inverted ("did we realise"). The grammatical structure of these sentences is shown in the diagram below. Not until [1st clause: subject + auxiliary verb...] [2nd clause: auxiliary verb + subject...]. Here are some other examples, with brackets around the two clauses: Not until [the rain stopped] [could we see the view of the ocean]. Not until [the president resigned] [did the protests stop]. Not until [my daughter called me] [did I stop worrying about her]. (from http://www.learnersdictionary.com/qa/sentences-that-begin-with-not-until) I hope this helps.

There is no inversion. You could invert it like this: "Not until recently has it become...."