I have had Luminar 4 since Dec 2019 but could not use it due to graphics card issues on my computer. Tried everything in the book to no avail. Eventually I replaced by graphics card (it failed after 6 years) and voila Luminar 4 is back. I bought it for its AI sky replacement feature and it certainly worked very well for my example.
The original, post processed in lightroom. The day was cloudy and dull and I tried to brighten up a bit.
The sky was replaced with a stock sky that came with Luminar. It took me about 3 seconds once I figured out the steps.