not specific to cc. Saw this once, and only once ever, in a match set i had with kirah. I ended a guardstring and was bunkered (non clash) about a full second after the string was finished and circuit was reduced by 100%- similar to whats shown in link. We had a few lulz after and concluded that the circuit cost maybe be still be deducted up until a certain number of frames has elapsed post-guardstun (regardless of clash occuring). Either that or it's a bug lol.
Like i said, only saw it once and never again. It's actually archived but there are too many vids to search through unfortunately. =/