Blocks will either go invisible for a moment when placing slabs on hoppers. Also when minning blocks have become completely see through. I will provide screen shots.
What I expected to happen was...:
Not to see through solid blocks.
What actually happened was...:
Blocks became transparent. Sometimes for a brief moment. Sometimes until I mined out the block.
Steps to Reproduce:
1. Strip mining at Y level 5
2. Cleared the block and the space turned black but could also see glowing squid in the distance along with spider eyes.
3. Blocks stayed transparent till I mined the transparent bloack
4. Also when placing slabs on top of hopper's, the slab will become transparent with only the outline for a brief moment. Then renders fully. Happens a lot of other times off in the distance as well. Just when running around the world.
This report is invalid as your game was modified when experiencing this issue. The F3 debug screen within the screenshots you've provided states that you're running OptiFine and this modification is not supported nor developed by Mojang Studios.