Reanimation is handled by the server in MP, but you're doing things on the client. The server doesn't know about it.
Picking up & dropping the corpse syncs something with the server, so now it knows what to do.
So you need to figure out how to make sure that things run on the server at the right time. Easier said than done.
Decompiling the java source code always helps with figuring out why something doesn't work.
If server was set to longer growth time (i think there is such option), then vegetables would stay longer in their "ready to harvest" state. By default in game cabbages take 2 weeks to grow, realistically it takes about 3 months.