Reset Preferences settings :
edit -> preferences -> general
click on " reset preferences on quit"
restart photoshop .
let us know if that helps.
I tried this and it allowed me to apply the liquify filter to a non-smart layer. however after closing the liquify window, I then tried to open liquify again. Instead of opening the window to edit liquify in, it further distorted the area I had just previously adjusted with the liquify tool. I then deleted the layer. made a new copy of the background layer and attempted to apply the liquify filter again. This time it also failed to open the liquify editor window and just reapplied the same liquify distortion as before. Not sure whats going on here.
I had the same issue - read somewhere that converting to smart layer is the fix - this helped for a couple a times and then stopped working .
Then i went in to edit > preference > performance and unchecked the use graphics processor setting - this worked and now i can use filters on my layers .
I'm thinking this is a driver issue - btw i use Nvidia Gtx 970 and win10 .
Hope that helps.
nope - sorry - same issue again.