To change the dino level use the difficulty override not the difficulty itself. Had the same issue. I put the difficulty override up to 7.5 and now I can find dinos at lvl 180. You'll still find some lower levels but way more higher levels
It started as 5000 when they first gave us the nitrado servers but it changed to 1000 then the option was took off the cap is 250 per tribe or personal owned it's bs really. It may change in the future tho we rang them recently about it now we're splitting a 6 person tribe up x