This is with version 430.7 on a Mac. I did not try the new beta version.
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Pick a tune with an auto-finish
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Make window as narrow as possible (not sure this is necessary to reproduce)
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Menu → Download.
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Click Record next playback
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Click red record button in the bottom left corner
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As soon as you hear a couple of count-in press the space bar
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Repeat 3 to 5 but let the tune play to the end
→ the recording never downloads and the record button stays red