A321 Captain reported a fuel ECAM message during cruise. Flight diverted for maintenance action then departed for original destination.

Narrative

During cruise; about 40 minutes into the flight we had a FUEL ACT XFR FAULT. FO (First Officer) was PF; so he remained the PF while I executed the procedures. ECAM simply displays PROC…APPLY in response to this fault. Fortunately; I always take note of what fuel we have in the Center and ACT (Additional Center Tank) tanks prior to pushback. We had 4460 lbs still trapped in the AFT1 tank; which is what I had noted at the gate. This is a QRH procedure. It appeared we had a fault in the ACT system fault which drove us to the FUEL ACT SYSTEM FAULT (A321NX) checklist; which isolates the fuel in the CTR and ACT tanks (about 9;000 LBS trapped) and limits flight time to 120 minutes; which we ended up being less than that in flight; but total block was 2:18.After consulting with Dispatch and Maintenance Control; and given we were heading in the direction of ZZZ (weather there was VFR) and we close to equidistant to ZZZ1; it was collectively decided that we would divert to ZZZ. We knew; however; that we would be overweight by around 5;000 LBS requiring overweight landing considerations. FO advised ZZZ Center; given that overweight landing is an urgent condition. With that in mind we elected to buy time and hold to make sure we had all SOP's complied; make double sure we were doing the right procedure and not just rushing to get on the ground. Interesting to note; once on with ZZZ Approach and given we were asked if we needed assistance. I told them the nature of the issue and landing overweight. They said they need a request for priority handling and they would do it. However; we were already a priority; and not an urgent priority. But it was not the time to debate definitions and I agreed that we are an 'urgent priority aircraft'; but would not anticipate needing assistance or to be followed to the gate. FO did a great job as PF with a nice approach and landing. Logbook entry made at the gate. Maintenance evaluated and after recycling fuel pumps did a transfer of fuel out of the AFT 1 and applied MEL 28-XXX for ACT AUTO TRANSFER. However; the maintenance tech was taking a fair amount of time trying to get the data from the MCDU (Multi-purpose Control Display Unit) needed for the overweight landing. Given that we were not sure how much time was going to be needed and the fact the #1FA (Flight Attendant) was concerned that there were some passengers that were feeling anxiety due to the diversion; and one particular passenger was fairly overweigh and had trouble fitting into the lav; and wanted to go inside to use the facilities. I worked with the gate agent and deplane. After the fact; one of the gate managers came on and mentioned that the gate agent should have cleared it with him; and the restaurants were already starting to close. We had a cordial conversation about it; and it was fine. However; I explained to him that was transparent to me; and I made my decision with the gate agent; not to mention the FA's be stressed with passengers wondering when were were going to depart given the nature of 'rolling delays'. I also advised Dispatch and told them my decision to the deplaning. We had 2 passengers elect to stay in ZZZ; if I recall that correctly. After about 1:10 on the ground; the MEL was applied and given the parameters during the landing; the overweight landing was not a factor and no inspection was needed. We re boarded the passengers; and pushed 1:40 after block in. Report was filed; as well.