That's odd, AMD hasn't change the form factor for their HSF on the desktop platform since Socket 754/940.
I'm betting its the boards themselves that are causing the incompatibilities due to the I/O covers and sizeable heatsinks on the VRMs. I get a warning from PCPartpicker that the board may have issues with the fitting on the La Grand Macho and require an adapter (?? dunno how that would work ??) and I'd have to measure it to ensure it fits.
The Macho is an amazing performer, and I was fairly sure I was going with an H20 AIO on this build, but the Macho offers legit performance and the added benefit of directing more airflow over the VRM area, so I'm going to have to accept its $80 price tag if I want to keep the CPU and board cool and cut down on fan noise as much as I possibly can (my current build has a first gen H80 with terrible pump cavitation that I never RMA'd).
AMD Ryzen R5 2600x, Asus Prime x470 Pro, Sapphire Nitro Fury 4GB, HP EX920 512GB NVMe SSD, 16GB Corsair Vengeance RGB Pro, 4TB WD Red HDD, Thermaltake Level 10 GT Snow Ed, Win 10 Pro