I am thinking you would have a vent tube that is plugged, preventing the hydraulic system from essentially resetting to its resting point (that is, pucks retracted and all well). This same effect might be caused by some other functioning part, but this is my best (and cheapest!) guess.
https://www.pelicanparts.com/catalog/images/SuperStock-Priority/911-355-013-13-M100.jpg
But I am a little wary of the rebuild on your brake booster - no evidence at all but is the tech. who did it experienced in this? It's just another item that throws pressure at your system - would be great to compare it to an OEM item.
Best of luck!