I am using LAB and curves to do some color matching with images and have run into a strange problem. It should be noted that I have been working on a ton of images over the last few days using the same method and haven't had this problem before. This is the first time I have tried to do this since updating Photoshop this morning. I'm also using the most recent version. I make my selection that I wish to alter and create a curves adjustment layer. Shift+Ctrl click on the second color selection. With that color point selected in the curves dialogue box, I click on output to change the number but the box disappears. I then click that point again to select it, the box appears again, and when I click the box to type in a number the box disappears again. I have already restarted my computer, reset the preferences, tried another file, and cursed. I'd greatly appreciate some help or ideas. Thanks! RackMultipart20180516102398xw2-5cb858fe-85d8-41ec-8929-15df66c4536f-88499503.PNGRackMultipart201805161131318eu-47e006fe-b358-4f53-9b93-1b4d5a324853-1521631557.PNGRackMultipart2018051699688rsxq-7c98b9ed-57a9-4873-8189-31062c839485-1105538071.PNG
Like Earth, I'm not having any problem once an anchor is placed and the numbers show up in the input/output fields.
Since you do have an anchor, and you just updated to the latest, perhaps you need to clear your preferences (being sure to save whatever presets you haven't saved first). I'm running High Sierra on Mac. It could be a bug in your system if nothing works and you're on Windows.
I have tried this same process on a Mac with the latest update and there is no problem. I have the problem on a Surface Pro running Windows 10. So I guess the problem is how the Surface is interacting with the update. I will try to clear my preferences.
I had the same problem, unable to enter output value. Going to post
my fix here in case others come here looking for solution as I did (and not
wanting to reset everything)... so it appears to be bug from the properties tab
being of a certain size and/or location. Move it about, first try placing
properties back into the right side bar. If that doesn't work make it separate
again and make the window really large. After doing that I have it back pretty
much where it was originally and output still available.