Seems like the maximum grain length you would actually get was only 64 frames (around 1.5 ms), no matter what the value was set to.
I think it has been like this for at least a month. The bug has been fixed already, and the next release will sound correct.
Please let me know if you are using this bug to make a special effect, or it turns out that you are unable to get the same sound (and you really wanted that sound). If so, I will add a compatibility mode to the program.
(Just lowering the grain length manually will not produce the same sound since "ramp" and "overlap" depends on the "length' value. So we need a compatibility mode to get the same sound as before the bug was fixed.)
Heads up: Crippled grain length in granulation (before Radium 5.9.14)
Re: Heads up: Crippled grain length in granulation (before Radium 5.9.14)
Oops, it wasn't that bad. The limit was around around 100ms, not 64 frames / 1.5ms. 1.5ms would have been discovered far earlier, of course.