Delay in Crafting GUI Update

Simply put, I have been trying my hand at creating a Custom Crafting table, and for the most part it's working just fine. Except for one, small issue. The system is set up in a way that utilizes the "When Slot Contents Change" trigger for each input slot, but any time you attempt this, it doesn't work at first glance. If you close out of the gui and then reopen it however, the desired effect is achieved (components in the input slots, desired item shown in the output slot), and the same applies if you remove an item and reopen the gui (desired item is removed from the output slot). This was done so that it would function as the vanilla crafting bench does, and while you can technically just work around this with the whole close and re-open thing, it's certainly been a bit of a headache.

(Procedure for reference)

One thing I have noticed however in my many hours scouring the forums, is that in every mention of Custom Crafting tables on here, and every tutorial shown online (old and young alike) involves use of a "button". While this could potentially be what I'm missing here, it's evident enough that a button is not used in vanilla Minecraft and, therefore, not what I'd prefer to do if it's at all avoidable. Is this issue I've been experiencing part of some missing piece of code that I've failed to realize, or is this simply a limitation on MCreator's part?