dvirov

can confirm

i responded here with attached files
MC-302821

it seems like new leve.dat fixed the problem

i created new world and transperd the folders of poi,region and entities

when i tried to use the bugged level.dat it said invalid player data

i could not reproduce the bug after that even after relogging and restarting the luncher

the first world is still corrupted and cant be accessed

happaned to me right now

just tried to open save i created on this snapshot the day before

new leve.dat fixed the problem

attaching log and level.dat of the curoppted world

Ok, so I was going to record the bug as yo asked and then I found out that I had Attribute mining efficiency = 100 and this is what caused the mining to be too fast, so actually it seems that the bug is that mining efficiency attribute does not affect tools whose mining speed = 1 
so if the mining efficiency is not a bug you can close this issue and sorry for bothering you if it is a bug should i open another issue or edit this one ?

its instamine even iron ore and even if the speed set to 1.00001