To reproduce:
1. Open attached project;
2. Run the "TestScene" scene;
3. Press Button "2" then "1".

Expected behavior: when button "1" is pressed after button "2", the button "2" comes back to normal, not "disabled".
Actual behavior: buttons being "disabled " after pressing them, and becomes normal, when mouse pointer is on button.

Reproduced in: 5.5.0f3;
Not reproduced in 5.3.6f1; 5.4.3f1

Note: very similar case 826310
Note: if you use mouse hover to trigger around button it will become normal again.