When you pause actionlist and resume all during one action then after action ends the actionlist is paused. It happens because variable pauseWhenActionFinishes in ActionList class is set to true, and when calling resume using KickStarter.actionListManager.Resume(c); it isn't set to false.
I have AC 1.53, but it isn't mentioned in changelog for AC 1.54, so I assume that it wasn't fixed.
Comments
Are you certain the second Action is not running? Try replacing it with an Engine: End game Action to be sure - the game will end as soon as it's triggered.
Though you're correct v1.54 didn't have any changes made to this area, I was testing with the latest version - so try downloading the same and see if that makes a difference, in a backup project.
Therefore, if you resume it while this is occuring, the ActionList hasn't yet been paused - and so cannot be resumed.