It looks like the HotBar UMG blueprint got corrupted from a bug in 4.10. I will rebuild the hotbar widget from scratch and include it in the 1.3 update this should help.
an Unreal bug probably just garbled something in the blueprint, it really makes no sense why it’s bugging out now the way it is.
*** Update ***
It seems to be an issue with the slots themselves in the hotbar being corrupted. I guess at runtime it’s triggering some glitch that it ignores when you play in editor.
It’s 6:30am now so I’ll create a workaround for the UMG bug tomorrow and post it asap.
Like toxic gaming just mentioned there are events that fire when you equip/unequip items. If you look in the InventoryManagerComponent it might be a little overwhelming at first but the functions are named very descriptively. You can also use break points to step through and help find the spot that might be ideal for you to add your custom logic.
I would suggest putting your logic you want into it’s own function and then setting up some simple checks during the Equip/Unequip functions that call your logic when you want to.
You can also take a look at UpdateEquippedStats() if you want a more general example of a function that always gets called when something is equipped or unequipped. If you search references to that function it might help you figure out a good spot in the code to add your logic.
Depending on what you want to do you might want to add it in the PlayerCharacter when something is equipped/Unequipped it fires an OnRep_Notify for that equipment slot.
So it’s a great place to add some custom logic if it’s character related.