Photoshop tool pointer disappears on LG UltraFine 5k

I finally broke down and upgraded to Adobe Acrobat Pro DC and both the problem with the cursor and the screen going black went away. It seems that the problem was with the Acrobat Pro X version and the discontinuation of support by Adobe. All solved on my end.

I have have the same issue and will try the suggestion below of enlarging the cursor arrow size. However, in addition, when I'm using my Adobe software, it will also frequently cause the screen to go full black. The LG UltraFine Display will return if I hit escape or click the cursor outside of the Adobe file. It's quite annoying. I only have this cursor and black screen problem with Adobe. These problems do not occur when I am just using my laptop.

Try changing the OS System Preference for changing the system mouse size. Go to Apple>System Preferences - choose the Accessibility icon and in the Display area, you'll see the ability to change the Cursor size. Please note - it won't change the actual pixel size of a brush - when you paint, the icon'll be bigger than the pixels you brush - but at least you'll be able to see the cursor. It takes a bit of getting-used-to.