Blocks are invisible for a split-second when placed.

I have this bug too, i hope it will get fixed, but you can change your render distance and then change it back to your old render distance.

It is because of the snapshots. The block is updationg and can take AGES to update. Try f3 and A at the same time. This will refresh the chunks and SHOULD make the block appear. 🙂

Blocks appear automatically after a second by itself. But before it wasn't disappearing.