How to reproduce:
Kdenlive version 0.7.9 rev. 5427
Project Tree, Right Click, Add Color Clip
Drag to Video 1
Right Click Color Clip on Video 1
Add Video Effect, Hue Shift
Click the clock for Add Key Frames
At the bottom right corner of that window is a number, probably 0.
Change that number using the keyboard to 150
Press Enter. The Hue line will change, but the key frame value will not.
If you instead use the mouse on the Hue line, that will work.
If you double click the value at the top of the window for key frame 1, you can edit with the keyboard
So in summary, 3 ways to change the value. Only 2 of them work.