In Rawlinson's demo drive a few months back he noted that some of the switchgear didn't have the tactile precision he wanted and that they were going to have to work on the detents and the spring stiffness. He specifically likened the feel he wanted to that of a Swiss watch, something no reviewers seem to have found in the switchgear. In an interview soon after his demo drive, he mentioned the difficulty they were still having in getting the quality they demanded from suppliers. It's possible that work on switchgear changes was started some time ago, but the suppliers haven't yet gotten the modified parts to the factory, and Lucid is trying to buy a little more time. (Remember that the cars used in the Production Preview were billed as pre-production cars.)
As the noise attenuation seems to relate mostly to tire noise in the rear seats, there may be something that can still be done with sound-deadening material around the rear wheel wells or behind and under the seats. Perhaps since Lucid's sound engineers didn't notice the problem in the measurements they made, they decided they could dispense with some of the sound deadening material that was available but, now that they are confronted with complaints, they can make use of it fairly quickly.
Software is done in-house and, once the right players are on board, time is the critical element in getting it right.
The first two scenarios are speculation, of course, but these are not far-fetched scenarios in which a few more weeks might give Lucid time to close some quality gaps.