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hi,

in 11.5.0, the split clip behavior has changed (see attached gif) :
eg. in previous versions, splitting a clip of 10frames in half would create 2 clips of 5 frames each, now clip A is 5frames (ok), but clip B is 10frames with the first 5 frames being blank.
I believe this is a bug.

thanks

Yes, it's been reported already : viewtopic.php?f=10&t=13957
It will be fixed in the new release.