It helps that the CMA will have softened Microsoft prior to them needing to meet with the EU regulators. In order for negotiations to take place regarding concessions and divestment it requires both parties to be willing to sit at the table. With the CMA Microsoft said no to both discussing concessions and divestment when they were proposed. After the CMA threw the hammer down Microsoft were more than willing to discuss concessions with the EU and they are now back with the CMA discussing divestment.
Seriously, if you haven't yet go back and listen to the FTC trial. The level of incompetence was beyond belief. If you want to see what the discourse was like here at the time then start here:
It was
bad. If you are ever in trouble, get forced to take a public attorney and you're assigned any of the FTC lawyers that dealt with this trial then do yourself a favour, skip going to court and just put yourself in jail.
Microsoft themselves said that they would no longer persue the deal if the FTC got the PI. They may have been bluffing to create a sense of urgency due to the deal deadline fast approaching but if we assume that's true then they would no longer have needed to talk to the CMA and whatever concessions they agreed to with the EU also become irrelevant.
If I were to take a guess then it would be that Microsoft will have gone to the CMA with a divestment proposal for them to consider on the condition that the FTC's PI was unsuccessful. Hence the CMA have now put the wheels in motion to
start doing the necessary work to make a decision on the divestment proposal which will now run through to (up to) August.