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Might be the same issue as was fixed with https://github.com/KDE/kdenlive/commit/50085b9fca6690e22145a0afbf3882746877bf68 for kdenlive.
I have created a pull request to the Kwave github repository for the same: https://github.com/KDE/kwave/pull/2 It is similarly done as the Kdenlive example.
The MR I had created for this enhancement has been merged - this would be visible soon in KWave releases. I am closing this bug.