Animate birth rate?

[Fabrice]

Rebooting should have no effect, to be honest….perhaps something else was the issue (ex: maybe the ‘set key’ button was pressed instead of auto key, when changing values?)

I do a lot of animation so I didnt forgot the auto key mode, it really didnt work
but I think it's more a Max issue as some other things (especially viewports and animation curves manipulation) in Max where acting weird until I turn it off.
But still...I posted way too fast