HI
This looks like a bug to me.
Having selected a series of clips using Ctr +A , On entering -0.25 and selecting to Append the effect chain to otherselected clips.....

ALL the clips correctly get the -0.25 correction BUT ALL clips EXCEPT the selected clip retain the default 0.25 correction. .... i.e. They end up with two effects as the original default is not removed....

essentially they don't change.... They get the -0.25 and the original default 0.25 meaning they return to normal. Only the selected clip from the group gets changed.
I have referred this post to NCH
Nat