This might be a fix Re: Songs won't stop downloading to iPhone.
I have two devices exhibiting this issue - an iPhone 6 and iPad Air. Following the directions above - I removed the iPad Air with iTunes from the list described under my account, then re-enabled iCloud Music Library on iPad and added a new album to iTunes - sure enough it showed up on the iPad as iTunes match streaming and not downloaded to iPad. So I tossed a few more albums into iTunes - they also showed up on the iPad without downloading.
Interesting to note - that doing this only for the iPad seems to have resolved the issue for my iPhone as well - new items are showing up on iPhone without downloading.
Fingers crossed - so far so good with about 5 new albums dropped onto iTunes for Match.