Laptop is an HP 15-ef2127wm.
AMD's information page on the Ryzen 5 5500U does not list the maximum amount of RAM supported, only the speed.
HP specifications page for this model do not list the maximum RAM supported.
Sites like Crucial do list the system, and show that 32 GB (2x 16GB) is the max, but 32 GB modules exist, so I am unsure if the maximum is correct, or if it was written by someone not aware of 32 GB modules.
I have tweeted and DM'ed AMDCare on Twitter with this, to no reply.
Thanks!