EXACT same thing happened to me second day I had my new 2020 Ascent. Mechanic at dealer knew all about the problem and thought the problem had been fixed for 2020 but obviously it has not been. Had to disconnect battery to resolve it. Ridiculous.I had this same thing happen. The manual latch in the back panel did not work. I ended up taking it to the dealership and they disconnected the battery to reset the system. It has been over a month and it hasn't happened again.
The service department did say they sent the information on the issue to Subaru. I would recommend talking to someone at your dealership so that it can be passed along to Subaru. The more people that have this issue the more likely they will look into fixing it.