I have recently noticed something strange with Lightroom. Normally, I work my way down the Develop module making basic adjustments, using the various tools, and so on; the last thing I do is Upright or Manual lens corrections. However, I apply Lens profiles at the very beginning (because it makes a difference). Recently I noticed that when I apply Upright or Manual Lens corrections, Lightroom seems to temporarily disable any other corrections, apply the lens correction (which always seems to take forever), and reapplies the other corrections. I found this out after noticing minor black and white clipping areas temporarily reappear on a photo I had corrected with an adjustment brush while applying a Manual Lens correction.
I find this behaviour odd and do not know if it has any impact on any other corrections like adjustment brush correction (in this case I started wondering if Lightroom readjusts the adjustment brush area or not).