You
do have the needed SWS extensions installed ?!
I am sorry for the hassle.
The Custom Action i made is a Cycle Action and i think i did something wrong:
I exported the Action from my Reaper Action List but i think i had to export it from my Cycle Action List.
So here it is:
https://www.dropbox.com/s/agel6xedz5...Track.INI?dl=0
a) So you open Cycle Action Editor (you find it under main menu "Extensions")
b) Click on the import/export button and choose "import in selection main"
c) Choose the downloaded Cycle Action
d) Click on "apply"
Now, the Cycle Action will be present in your Reaper Action List and you can assign it to a keycommand.
Maybe some Cycle Action expert can chime in if this is still not the right workflow but please try the above and lemme know if it worked out for you !