When U-Point masks are created they often includes that should not be masked. One example is that creating a U-Point mask of a bird in a tree also captures the branches as part of that mask. There should be some way to remove items from the mask.
The current method of “Protecting” certain areas only seems to reduce the effect of the masking, not remove it so perhaps there could be some way to paint out part of the mask or, failing that, some strength slider for the Protect functionality to completely protect those areas that should not be part of the mask.
Here are two methods I’ve tried with success: First, the brush tool. It’s a little tedious, but it works. Second, Viveza in the Nik Collection. It may take a few tries to get the u-point in the right location, but if mask is set to View and the selected area is homogeneous, Viveza works well.
I have tried using the masking brush, but find that the Auto mask does not do a very good job of differentiating the subject from the surrounding area and I end up having to do a fair bit of erasing. It works, but it is a lot of trouble and I always thought that the U-Point functionality was supposed to solve that problem. It would if I could just erase or truly protect some of it from adjustments. It would be even better if I could add to it as well.
I have never actually been a fan of the Nik collection, so I did not buy the latest version from Dxo. Given that, your second suggestion does not help me and my assumption has been that PL incorporated the Nik stuff into its functionality so that people did not have to also buy the Nik suite. I also assume, perhaps incorrectly, that the Dxo people have the goal of adding the Nik stuff to the PL UI at some point in the future.
I used PL to launch the Viveza app and what I founds that the control point in Viveza was no easier to adjust than the one in PL. It formed the same circle which also included the same branches. There were far fewer adjustment controls than in PL and, when the image is saved back to PL the adjustments did not show up in the tiff file used to send to Viveza.
I personally do not see what advantage there is in using the Nik functionality. It may be my lack of expertise using Nik, but I found the controls buried in PL to be easier to use and the adjustments showed up, while they did not when using Viveza.
I recently also used Viveza, because I had to adapt some local colors and light in a JPEG, where I did not have a RAW for. I find the PL U-points also much easier to use. The only advantage I could see in Viveza was, that one could stear RGB channels in addtion to HSL and that there was a “Layers” panel to manage the adjustments.