[MC-136381] Mycelium under non-full height blocks doesn't decay and spreads

I tested with enchantment tables and half slabs. Just go into creative, place mycelium next to some grass and put these items on it. Set /gamemode randomTickSpeed 100 and watch it not go away.

Linked issues

duplicates 1

MC-18091 Placing a stair block on a grass block, it will not turn to dirt. Resolved

Comments 2

Ezekiel 2018-08-24T00:42:55Z

Duplicate of MC-18091 – If you have not, please use the search function in the future, to see if your bug has already been submitted.

Anon 2018-08-24T02:07:13Z

Mycelium wasn't mentioned in the other posts so my search turned up nothing. Why are these blocks considered transparent? It doesn't make sense.