Hello there Robaschi,
What I see here is that you have some overlapped events, you need to be very careful since Construct 2 reads the code lines in the order as they were written, and sometimes the system replaces similar events for the one that has been created at first.
Try changing the 11th line to "platform is jumping" instead of "Up arrow is down" and let's see what happens.
You also don't need the "On A key down" in event 9 to 11 since this condition is already tested line 7 and common to all those sub-events.
You can post the URL to your capx as text that we will copy in the URL bar, That would likely be easy, because twice the screenshots you post actually fail to focus/display the events of where your issue lies (on the first screenshot, the events about moving/stopped are collapsed instead of being expanded unfortunately)
I was about to post the capx myself, actually, so that someone can tinker with the commands and events and whatnot.
And since I still don't have enough reputation, here's a spaced out link.
ht tps : //www . dropbox . com/s/fi6xrwoqkx50qhq/Test%20Two . capx?dl=0
Just a note I added some more stuff, such as a ladder climbing sequence. I'm still working on that in the meantime.