Ableton Forum

Live 12's 'Time Warp' MIDI Tool can speed up/slow down your notes within a clip..

you could try this one:
https://www.soundsuite.nl/lfo-midi/

the slider is the number box. not the best name for it..

The beta test area would certainly benefit from more use of the words beastly and slipshod

You didn't miss anything. It just doesn't work that way. Sampler can use metadata embedded in samples to set the correct key/zone etc but it does not use info taken from a sample's name.

The slices start at C1

Is the 'Next' action set to 100% ? If it's not, it can use the second action (defaults 'No Action') which won't play again.

If I understand your issue correctly, try this:
While in map mode, select your macro and run the DT briefly, stop it, and then use Undo in Live to cycle through the sent CC messages.

following your video i could recreate the dropped note. sometimes a note is missed, other times it's played late.

For random notes that don't repeat in clusters, you could use a Scale device > Arpeggiator's 'Random Other' style (the first two notes are sometimes the same but the rest don't repeat)

hold shift and drag it

I've never really used program changes for VSTs but I just gave it a try using both the VST2 and VST3 versions of NI Massive.
I can only confirm what you're seeing:
VST2 version switches presets as expected
VST3 does not switch presets at all.

what you're seeing is the tempo range divided by 128 (the resolution of your midi knob)

so 105 > 174 is a range of 69, divided by 128 = 0.54
so your knob is stepping in increments of 0.54 (105 > 105.54 > 106.09 etc.)

Did you set Simpler/Sampler's device Volume to 0db? They default to -12db