A320 pilot reported the parking brake failed during pushback but was recovered after consultation with maintenance.

Narrative

After push back with one engine operating; ground crew asked me for parking brake; I set the parking brake ON; and asked him to remove; disconnect; and give me signals. Shortly after; the airplane started to move forward; and as I applied the manual brakes; the [pushback crew]; requested me to apply the brakes. I asked him if everything was good; and he replied yes. I confirmed that the parking brake was on; and at that moment; there was no pressure on the indicator. I communicated to the [pushback crew] that we lost the parking brake; and might have to go back to the gate. I recycled the parking brake lever several times; but did not work. [Pushback crew] told me the tow bar was already disconnected and he was only plugged with the headset. I asked him to disconnect and give me signals in order to coordinate accordingly. Then I called Maintenance ZZZ; and asked for any advice. They told me to call ZZZ1; which is normal procedure. At that point; I recycled the A/Skid & N/W. STRG switch; and the parking brake was recovered. I checked all indications and parameters; and after several cycles; the operation of the parking brake was normal. We continued with Aircraft X uneventful to ZZZ1.