Let's say I have an image I'm working in LR, I right click and select edit original in Photoshop, it opens in Photoshop, I remove a whole person, or add a layer and clone things, save it, go back to Lightroom, the image I see is not refreshed to reflect the new image in the Develop module, although it shows the changes in the library module. Only way to have the Develop module to show me the changes is to restart LR. This is pretty bad... I keep trying to move from LR 5.7 to 2015 and in every single version I found something that makes it unusable.
I can't make it happen all the time, I'm not sure what triggers it, but mostly happens on TIF files with many layers. I would say I hit this problem about70% of the time with real files from real jobs, if I try to create the problem on purpose, I can't. The problem is that I'm getting it so often that makes work with this version of LR extremely complicated.