Custom Resolution Utility (CRU)

[Elore]

Okay, here's my issue. I tried to use CRU to add lower refresh rates for better video playback (monitor is a HP w2408h connected via HDMI with a HDMI splitter inbetween, video card a R9 270X).

I added 1920x1200@50hz, and it worked perfectly (as opposed to the broken 1920x1080@50hz that the monitor sort of supports by default).
Then I added 1920x1200@48hz, and it, too, worked perfectly (as reported by madVR and ReClock).

Then I decided to mess around and added 1920x1200@70hz, but of course it wouldn't do that, so I deleted it again.

Except now it throws up input signal out of range errors when trying to switch to 48hz (50 and 60 still work).

How can that happen? It absolutely did work the first time. Tried with both LCD standard and reduced, also tried 1080p48, but that didn't work, either. Am I just SOL here and broke it somehow?