I tried to mount 8 cogs Sun Race cassette on the freehub of a trainer which I think is rated as "Shimano" (T2875-01 freehub). The cogs fit ok (with a spacer between the hub and the big cog). However, the lock ring can not be screwed - it is like the freehub has a little smaller internal diameter (maybe 0.1-0.2 mm) or a different pitch. I tried another lock ring, from SRAM 22 (11 speed), but it behaves the same. I try to find a solution and find a 8 speed compatible cassette / lock ring, so I am wondering:

Are the lock rings from SRAM 22 (11 cogs) fully compatible with Shimano 11 cogs cassette? If not, this could explain my issue.
If not, then: are 8 speed Shimano lock rings compatible with 11 Shimano lock rings? If yes, this could solve my issue.