Similar issues even with just 2 DIMMs with some XMP/EXPO profiles not working on AMD systems because of board/CPU limits. It should technically work, but for whatever reason it just can’t handle it and speeds need to be dropped or the timings loosened a bit even though the RMA itself is rated for that.

Not that the higher speeds are even necessary for 90% of users outside extreme overclocking. DDR5 6000 is basically where you reach diminishing returns anyway, and that’s often where that limit seems to appear.