In an effort to simplify things for you, I edited your project. Here are a couple things I noticed:
1 - Because you are disabling some event groups, it would be better to remove all your events to set the character to idle from these groups.
2 - You have events for letting go of the directions as well as the block so I combined those all into 1 event.
3 - Because you want the idle to be happening when the 3 direction keys are not pressed, it would be best to use the inverted "is down" event, not the "on key released" event so I changed it to do that.
4 - This has nothing to do with the above bug but, you had a couple "every tick" events combined with other conditions. "Every tick" does not change when an event happens when there are other conditions. In other words, if a condition is true, it will fire every tick without having "every tick" specified until it is no longer true. "Every Tick" should only be used if you really want something to happen every tick no matter what. There is a blog post about that but you'll have to look it up.
There were a couple other things I changed but if you look over the project, you should see the differences.