Delete Silence tool detection is wrong when long duration of audio is selected or >500 segments

To reproduce:

• Open "Delete Silence" tool and select some sane thresholds
• Select ~60 min or longer of audio and click "Scan"

Detected silence segments include long sections of audio, as if the thresholds were invisibly changed. The number of segments detected is also much smaller than it should be.

If you reduce the audio selection slowly (e.g. from 60min to 50min, then 40min, 30min, etc.) and scan at every duration, at some point, it will start working correctly again. Number of segments detected goes from something like 26 to 498 when I shorten the duration from 34min to 33min. This makes no sense, because it longer duration must have more segments.

From the behavior, it seems like when more than 500 segments of silence are present, it gives the wrong result.