Those mother fuckersIf you're talking about the 11 speed stuff, it's a known issue:
Shimano M5100 11-51 11 speed Cassette
I was able to finally get my hands on one of these cassettes. As you can see it has very even cog spacing unlike the Shimano 11-46 cassette. I am using a SLX M7100 12 speed derailleur and the Shimano HG601 chain with a XT 11 speed shifter on my Trek Stache. I have about 100 miles on it now...www.mtbr.com
I actually tried "shimming" it with cut pieces of a paper staples, but they eventually fell out. Looks like I was supposed to use bobby pins (oddly, I'm friends with the guy who used the bobby pins).
As @Westy wisely pointed out on another read, the answer is always more (fucking) shims.