Active Redstone Clocks/Observers stop working right when reloading game

I noticed my Observer chain froze when i re-loaded the world, and upon investigation noticed redstone clocks aren't being checked correctly upon game loading

Steps to reproduce:

1. Create some clocks with observers or hoppers (noticed it with the observer chain, put a hopper clock in there for testing, seems similarly affected)
2. Crash the game somehow. - OR - Save and quit as normal, back to launcher (unload minecraft entirely) [i was getting null-pointer error(s) in this snapshot when in spectator mode occasionally]
3. re-launch minecraft,
4. wonder what happened to all the fancy redstone

Symptoms: Observers 'freeze' in on state, or no-longer detect the opposite observer as having a state change. Hoppers seen to double their item transfer speed and glitch-(destroy or non-render) several items in their inventory. I had 8 items in the hopper, and after reload it was only 6 or 4 that i could pull out
It seems to cycle between broken-reloading and non-broken reloading.

Before: https://gyazo.com/cbd85da21bf3ff179124291c56137cab
After: https://gyazo.com/c578810470f7ae63e8470b3bbea78e41

Hopper (Normal/expected): https://gyazo.com/2b761236a48dcfe148642c2d4cf7fc55
Hopper (Super speed glitching): https://gyazo.com/0d4b1c9a5207da63f4326c57fb8ba784