The Draw Brush Polys setting does not display translucent Material in versions 4.17 and higher, instead, checking the option appears to do nothing. This issue does not occur in 4.16.3, this issue is labeled as a regression.
Versions Tested:
4.16.3 - CL: 3561208 - Issue does not occur
4.17.2 - CL: 3658906 - Issue occurs
4.18P4 - CL: 3685441 - Issue occurs
4.21.2 - CL4753647 - Issue does not occur
4.22.1 - CL6063286 - Issue occurs
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-51237 in the post.