Bug when you use the command /setworldspawn in a server 1.14.3

Hi, i' ve experimented an error when i created a world spawn point in a server, When you create it and then test it with another account (no admin) in order to see if there is any problem in Survival Mode, in an area where i used the command /setworldspawn, it doesn't allow you to break any block there, also grass or flowers, you can't break anything!

Another problem is the user, who is in Survival Mode, doesn't spawn exactly where i placed that command. I want to set a world spawn point exactly in the coordinates where i put in the command.

Example: /setworldspawn 100 40 -100

When the user die, you appear in 107 40 -91 or 92 40 -106, etc.