How to reproduce:
Create a new short sample, 64 or 100 samples long.
Generate a waveform or simply draw in any data
Right click on the sample, Advanced->Backwards
Click on Redo Filter several times
What should happen: The sample is identical or reversed from what it originally was
What happens: Data is lost from the edges of the sample and an interpolated value is inserted in the middle of the sample.
Also happens when you do this to a selection.